Journal Description
Clocks & Sleep
Clocks & Sleep
is a peer-reviewed, open access journal that investigates a wide range of sleep related topics and is published quarterly online by MDPI. The Australasian Chronobiology Society, Society for Light, Rhythms, and Circadian Health, and Swiss Society of Sleep Research, Sleep Medicine and Chronobiology are affiliated with Clocks & Sleep and their society members receive a discount on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High visibility: indexed within Scopus, ESCI (Web of Science), PubMed, PMC, FSTA, and other databases.
- Journal Rank: CiteScore - Q2 (Neuroscience (miscellaneous))
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 37 days after submission; acceptance to publication is undertaken in 4.7 days (median values for papers published in this journal in the first half of 2025).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Journal Cluster of Neurosciences: Brain Sciences, Neurology International, NeuroSci, Clinical and Translational Neuroscience, Neuroglia, Psychiatry International, Clocks & Sleep and Journal of Dementia and Alzheimer's Disease.
Impact Factor:
2.1 (2024);
5-Year Impact Factor:
2.5 (2024)
Latest Articles
Prevalence and Clinical Impact of Restless Legs Syndrome in Pediatric Populations with Attention-Deficit/Hyperactivity Disorder: A Systematic Review
Clocks & Sleep 2025, 7(3), 50; https://doi.org/10.3390/clockssleep7030050 - 17 Sep 2025
Abstract
Attention Deficit Hyperactivity Disorder (ADHD) is a prevalent disorder in the pediatric population. Furthermore, there appears to be a special relationship between ADHD and Restless Legs Syndrome (RLS). The objective of this review was therefore to provide an updated overview of the current
[...] Read more.
Attention Deficit Hyperactivity Disorder (ADHD) is a prevalent disorder in the pediatric population. Furthermore, there appears to be a special relationship between ADHD and Restless Legs Syndrome (RLS). The objective of this review was therefore to provide an updated overview of the current literature regarding the prevalence of RLS and its potential clinical impact in pediatric ADHD subjects (<18 years). A systematic literature review was carried out in May 2025 in the PubMed-Medline database according to PRISMA criteria. After evaluation by two readers of the 147 identified articles, 9 articles investigating the prevalence of RLS with or without assessment of its potential clinical impact were selected for this systematic literature review. The prevalence of RLS in children and adolescents with ADHD showed significant variation, ranging from 11% to 54%. One study found a significant impact of RLS on academic performance and life skills in pediatric ADHD subjects. Three studies highlighted higher severity of ADHD complaints in subjects with comorbid RLS. One study reported higher RLS severity scores in the ADHD+RLS group and significantly more severe scores in the “hyperactive-impulsive” ADHD subtype. Two studies identified a significant association between a family history of RLS and RLS+ADHD comorbidity. Compared with the general pediatric population, the prevalence of RLS appears to be higher in pediatric ADHD subjects. Finally, this comorbid sleep disorder could worsen the severity of ADHD symptoms and complicate its clinical management.
Full article
(This article belongs to the Section Disorders)
►
Show Figures
Open AccessArticle
Sleep Quality Assessment in Intensive Care Units: Comparing Actigraphy and the Richards Campbell Sleep Questionnaire—A Pilot Study in the Moroccan Context
by
Abdelmajid Lkoul, Keltouma Oumbarek, Youssef Bouchriti, Asmaa Jniene and Tarek Dendane
Clocks & Sleep 2025, 7(3), 49; https://doi.org/10.3390/clockssleep7030049 - 16 Sep 2025
Abstract
Sleep in intensive care unit (ICU) patients is frequently disrupted, which may adversely affect their overall health and recovery. Despite the implementation of various strategies to promote sleep, accurately assessing its quality remains complex. This pilot study aimed to evaluate both the quality
[...] Read more.
Sleep in intensive care unit (ICU) patients is frequently disrupted, which may adversely affect their overall health and recovery. Despite the implementation of various strategies to promote sleep, accurately assessing its quality remains complex. This pilot study aimed to evaluate both the quality and quantity of sleep in ICU patients using actigraphy (ACT) and the Richards–Campbell Sleep Questionnaire (RCSQ) and to compare the diagnostic performance of these two tools. We conducted a prospective observational study including 228 ICU patients. Sleep was assessed using both RCSQ and ACT. Receiver Operating Characteristic (ROC) curve analysis was used to evaluate the discriminative ability of each tool (Area Under the Curve [AUC], sensitivity, specificity), with optimal cut-off points determined using Youden’s Index. The Mann–Whitney U test was used to compare sleep parameters between patients classified as having good or poor sleep based on ACT measurements. The mean RCSQ score was 38.16 ± 17.09, indicating poor perceived sleep quality. Sleep onset latency (based on RCSQ) was 35.71 ± 21.44 min, with a mean of 40.32 ± 20.03 awakenings. According to ACT, sleep latency was 39.23 ± 22.09 min, and total sleep duration was 198.15 ± 128.42 min (approximately 3 h and 18 min), which is significantly below recommended levels. The average number of awakenings recorded was 24.85. In terms of diagnostic performance, the RCSQ demonstrated excellent discriminative ability (AUC = 1.00 for the total score), while ACT showed more variable results: total sleep duration had a good AUC of 0.91, while sleep latency showed a lower performance with an AUC of 0.50. The RCSQ proved to be more reliable than ACT in assessing sleep quality in ICU patients, providing consistent results across multiple parameters, including sleep depth, latency, and number of awakenings. Conversely, ACT yielded less consistent findings, particularly regarding sleep latency and nighttime interruptions. Further studies are warranted to refine objective tools for evaluating sleep in critically ill patients.
Full article
(This article belongs to the Section Disorders)
►▼
Show Figures

Figure 1
Open AccessArticle
Dissociating the Effects of Light at Night from Circadian Misalignment in a Neurodevelopmental Disorder Mouse Model Using Ultradian Light–Dark Cycles
by
Sophia Anne Marie B. Villanueva, Huei-Bin Wang, Kyle Nguyen-Ngo, Caihan Tony Chen, Gemma Stark, Gene D. Block, Cristina A. Ghiani and Christopher S. Colwell
Clocks & Sleep 2025, 7(3), 48; https://doi.org/10.3390/clockssleep7030048 - 15 Sep 2025
Abstract
Individuals with neurodevelopmental disorders (NDDs) often experience sleep disturbances and are frequently exposed to light during nighttime hours. Our previous studies using the Contactin-associated protein-like 2 (Cntnap2) knockout (KO) mouse model of NDDs demonstrated that nighttime light exposure adversely affected behavioral
[...] Read more.
Individuals with neurodevelopmental disorders (NDDs) often experience sleep disturbances and are frequently exposed to light during nighttime hours. Our previous studies using the Contactin-associated protein-like 2 (Cntnap2) knockout (KO) mouse model of NDDs demonstrated that nighttime light exposure adversely affected behavioral measures. In this study, we exposed wild-type (WT) and Cntnap2 KO mice to an ultradian lighting cycle (T7), which alternates 3.5 h of light and 3.5 h of darkness, hypothesizing that this lighting protocol would mimic the impact of nighttime light exposure seen in standard light–dark cycles with dim light at night (DLaN). However, adult WT and Cntnap2 KO mice held under the T7 cycle did not show the increased grooming behavior or reduced social interaction observed in Cntnap2 KO mice exposed to DLaN. The T7 cycle lengthened the circadian period and weakened the rhythm amplitude without abolishing rhythmicity in either genotype. Finally, opposite to DLaN, neither the T7 cycle nor constant darkness (DD) elicited an increase in cFos expression in the basolateral amygdala. These results demonstrate that the adverse effects of nighttime light exposure in an NDD model depend on the extent of the circadian disruption rather than light exposure alone, emphasizing the importance of circadian stability as a protective factor in NDDs.
Full article
(This article belongs to the Section Impact of Light & other Zeitgebers)
►▼
Show Figures

Figure 1
Open AccessReview
Sleep, Physical Activity, and Executive Functions in Students: A Narrative Review
by
Giulia Belluardo, Debora Meneo, Silvia Cerolini, Chiara Baglioni and Paola De Bartolo
Clocks & Sleep 2025, 7(3), 47; https://doi.org/10.3390/clockssleep7030047 - 4 Sep 2025
Abstract
The school and university periods represent a critical phase in individuals’ cognitive, emotional, and behavioural development. Numerous lifestyle factors can influence executive functions and high-level cognitive processes crucial for learning and behavioural adaptation. Sleep and physical activity are two variables that influence executive
[...] Read more.
The school and university periods represent a critical phase in individuals’ cognitive, emotional, and behavioural development. Numerous lifestyle factors can influence executive functions and high-level cognitive processes crucial for learning and behavioural adaptation. Sleep and physical activity are two variables that influence executive functions and that could be modified through behavioural interventions. Numerous scientific studies suggest that adequate sleep quality and duration are linked to improved cognitive performance. Similarly, regular physical exercise correlates with neurocognitive benefits. However, these two aspects of lifestyle are often compromised in students, resulting in attention difficulties, reduced working memory, and difficulty in inhibitory control, all aspects of non-optimal executive functioning. Even though the scientific literature separately explores “sleep and executive functions” and “physical activity and executive functions”, few studies have integrated the two factors to assess their combined effect on executive functioning, particularly within the student population. The present narrative review aims to outline an integrated theoretical framework of existing scientific literature and to identify any knowledge gaps that may guide future research. It could provide relevant insights for designing preventive or promotional interventions to enhance students’ cognitive performance and mental well-being.
Full article
(This article belongs to the Section Human Basic Research & Neuroimaging)
►▼
Show Figures

Figure 1
Open AccessReview
Concussion Disrupts Sleep in Adolescents: A Systematic Review and Meta-Analysis
by
Suleyman Noordeen, Poh Wang, Anna E. Strazda, Eszter Sara Arany, Mehmet Ergisi, Linghui Janice Yeo, Rebeka Popovic, Abinayan Mahendran, Mikail Khawaja, Kritika Grover, Mohammed Memon, Saahil Hegde, Connor S. Qiu, Charles Oulton and Yizhou Yu
Clocks & Sleep 2025, 7(3), 46; https://doi.org/10.3390/clockssleep7030046 - 29 Aug 2025
Abstract
Concussions significantly impact sleep quality among adolescents. Despite increasing recognition of these effects, the complex relationship between adolescent concussions and sleep disturbances is still not fully understood and presents mixed findings. Here, we conducted a systematic review and meta-analysis to assess how concussions
[...] Read more.
Concussions significantly impact sleep quality among adolescents. Despite increasing recognition of these effects, the complex relationship between adolescent concussions and sleep disturbances is still not fully understood and presents mixed findings. Here, we conducted a systematic review and meta-analysis to assess how concussions affect sleep-related symptoms in adolescents. We included papers presenting Pittsburgh Sleep Quality Index (PSQI) differences following concussion in high school and collegiate patients, with sleep measures recorded following concussion. Animal studies, research on participants with conditions other than concussion, non-English articles and papers failing to present PSQI data were excluded. We searched MEDLINE®, Embase®, CINAHL, Web of Science™, PsycINFO®, Google Scholar, and Cochrane Central Register of Controlled Trials databases until 23 August 2024. In addition, we performed hand-searching of relevant reference lists and conference proceedings to identify further studies. Risk of bias was assessed using the Newcastle–Ottawa scale. In total, we considered 4477 studies, with nine meeting the inclusion criteria. Our analysis involved 796 participants, 340 of whom had experienced a concussion. Analysis was carried out using the meta and metafor packages in R (version 4.0.0). We showed a deterioration in sleep quality post-concussion, as evidenced by increased PSQI (standardised mean difference 0.84; 95% CI 0.53–1.16; p < 0.0001). Subgroup and quality assessments confirmed the consistency of these findings. Since poor sleep quality impacts daytime activities, we analysed the relationship between concussion and daytime dysfunction. We showed that concussion is associated with a significant worsening of the daytime dysfunction score by 0.55 (95% CI 0.24–0.70; p = 0.006). We conclude that concussions impair both sleep quality and daytime functioning in adolescents. Our research underscores the need for systematic inclusion of sleep quality assessments in post-concussion protocols and calls for targeted interventions to manage sleep disturbances post-concussion to mitigate their broader impacts on daily functioning.
Full article
(This article belongs to the Section Disorders)
►▼
Show Figures

Figure 1
Open AccessArticle
The Acute Effects of Morning Bright Light on the Human White Adipose Tissue Transcriptome: Exploratory Post Hoc Analysis
by
Anhui Wang, Jeroen Vreijling, Aldo Jongejan, Valentina S. Rumanova, Ruth I. Versteeg, Andries Kalsbeek, Mireille J. Serlie, Susanne E. la Fleur, Peter H. Bisschop, Frank Baas and Dirk J. Stenvers
Clocks & Sleep 2025, 7(3), 45; https://doi.org/10.3390/clockssleep7030045 - 27 Aug 2025
Abstract
The circadian rhythm of the central brain clock in the suprachiasmatic nucleus (SCN) is synchronized by light. White adipose tissue (WAT) is one of the metabolic endocrine organs containing a molecular clock, and it is synchronized by the SCN. Excess WAT is a
[...] Read more.
The circadian rhythm of the central brain clock in the suprachiasmatic nucleus (SCN) is synchronized by light. White adipose tissue (WAT) is one of the metabolic endocrine organs containing a molecular clock, and it is synchronized by the SCN. Excess WAT is a risk factor for health issues including type 2 diabetes mellitus (DM2). We hypothesized that bright-light exposure would affect the human WAT transcriptome. Therefore, we analyzed WAT biopsies from two previously performed randomized cross-over trials (trial 1: n = 8 lean, healthy men, and trial 2: n = 8 men with obesity and DM2). From 7:30 h onwards, all the participants were exposed to either bright or dim light. Five hours later, we performed a subcutaneous abdominal WAT biopsy. RNA-sequencing results showed major group differences between men with obesity and DM2 and lean, healthy men as well as a differential effect of bright-light exposure. For example, gene sets encoding proteins involved in oxidative phosphorylation or respiratory chain complexes were down-regulated under bright-light conditions in lean, healthy men but up-regulated in men with obesity and DM2. In addition to evident group differences between men with obesity and DM2 and healthy lean subjects, autonomic or neuroendocrine signals resulting from bright-light exposure also differentially affect the WAT transcriptome.
Full article
(This article belongs to the Section Impact of Light & other Zeitgebers)
►▼
Show Figures

Figure 1
Open AccessArticle
Sleep Quality and Patient Activation in Chronic Disease: A Cross-Sectional Mediation Analysis
by
Christian J. Wiedermann, Verena Barbieri, Stefano Lombardo, Timon Gärtner, Klaus Eisendle, Giuliano Piccoliori, Adolf Engl and Dietmar Ausserhofer
Clocks & Sleep 2025, 7(3), 44; https://doi.org/10.3390/clockssleep7030044 - 22 Aug 2025
Abstract
Patient activation enhances self-management of chronic illnesses, and sleep quality is vital for health. The link between activation and sleep quality and the mediating role of chronic diseases remain underexplored. This study examined the association between patient activation and sleep quality, variations across
[...] Read more.
Patient activation enhances self-management of chronic illnesses, and sleep quality is vital for health. The link between activation and sleep quality and the mediating role of chronic diseases remain underexplored. This study examined the association between patient activation and sleep quality, variations across chronic disease groups, and whether chronic diseases mediate this relationship. A population-based cross-sectional survey in South Tyrol (Italy) included 2090 adults (55.0% response rate). Patient activation was measured using the Patient Activation Measure (PAM-10), and sleep quality was measured using the Brief Pittsburgh Sleep Quality Index (B-PSQI). The presence and number of chronic diseases were self-reported. Bivariate analyses, multiple linear regression, and mediation analyses (PROCESS) were performed. Among the participants, 918 (44%) reported at least one chronic disease. These individuals had poorer sleep (B-PSQI mean: 5.05 ± 3.26 vs. 3.66 ± 2.65; p < 0.001) and lower patient activation (PAM-10: 54.4 ± 12.7 vs. 57.2 ± 12.5; p < 0.001) than those without. A negative correlation between PAM-10 and B-PSQI was observed (r = −0.12, p < 0.001), with stronger associations in patients with hypertension and mental illness. In adjusted regressions, chronic disease, female sex, and older age predicted poorer sleep, whereas higher PAM-10 scores predicted better sleep. Mediation analyses showed that chronic disease partially mediated the relationship between patient activation and sleep quality, accounting for 4.7% to 6.3% of the total effect. Conclusions: Higher patient activation correlates with better sleep quality, although this relationship is partly mediated by the chronic disease burden. Sleep disturbances persist across chronic conditions, despite good self-management. These findings highlight the importance of adopting strategies to manage chronic diseases and sleep disturbances, acknowledging that while patient activation is statistically associated with sleep quality, the strength of this relationship is limited.
Full article
(This article belongs to the Section Disorders)
►▼
Show Figures

Figure 1
Open AccessCase Report
Successful Treatment of Secondary Hypersomnia Due to Complex Post-Traumatic Stress Disorder with Eye Movement Desensitization and Reprocessing: A Case Report
by
Vlad Bucurescu, Laure Peter-Derex, Maria Livia Fantini and Benjamin Putois
Clocks & Sleep 2025, 7(3), 43; https://doi.org/10.3390/clockssleep7030043 - 15 Aug 2025
Abstract
Hypersomnia may be classified as primary or secondary, with secondary hypersomnia arising from a variety of underlying causes. Thus, according to ICSD3-TR classification, the diagnosis of idiopathic hypersomnia (IH) is established based on (1) excessive daytime sleepiness (EDS); (2) electrophysiological findings including either
[...] Read more.
Hypersomnia may be classified as primary or secondary, with secondary hypersomnia arising from a variety of underlying causes. Thus, according to ICSD3-TR classification, the diagnosis of idiopathic hypersomnia (IH) is established based on (1) excessive daytime sleepiness (EDS); (2) electrophysiological findings including either a mean sleep latency of less than 8 min on the Multiple Sleep Latency Test (MSLT) or increased total sleep (≥11 h) on 24 h polysomnography; and (3) systematic elimination of other potential etiologies, including sleep deprivation, substances, and medical, psychiatric (notably mood disorders), or sleep disorders. Nevertheless, the clinical heterogeneity observed in IH fuels an ongoing debate, reflecting the limited understanding of its underlying pathophysiological mechanisms. This report describes the case of a patient presenting with a clinical and polysomnographic phenotype of IH (MSLT < 8 min). A comprehensive psychopathological evaluation was performed to explore the possibility of secondary hypersomnia, which revealed features consistent with complex post-traumatic stress disorder (c-PTSD). Psychotherapy focused on c-PTSD was administered with positive and objective results in hypersomnolence/EDS. This clinical improvement suggests a potential relationship between psychological trauma and hypersomnia, a connection that is rarely described in the literature and warrants further investigation. This case highlights the need for a comprehensive assessment of secondary factors, particularly complex trauma, even in the presence of a clinical and polysomnographic phenotype consistent with IH.
Full article
(This article belongs to the Section Disorders)
Open AccessArticle
Polygraphic Results in High-Risk Infants Aged Under 3 Months
by
Daniel Zenteno, Gerardo Torres-Puebla, Camila Sánchez, Rocío Gutiérrez, María José Elso and Pablo E. Brockmann
Clocks & Sleep 2025, 7(3), 42; https://doi.org/10.3390/clockssleep7030042 - 12 Aug 2025
Abstract
This study described and analyzed the results of cardiorespiratory polygraphic studies in infants under three months who were hospitalized and monitored due to suspected apneas. Methods: Cross-sectional study. Patients aged <3 months hospitalized from 2011 to 2023 were included. All were referred for
[...] Read more.
This study described and analyzed the results of cardiorespiratory polygraphic studies in infants under three months who were hospitalized and monitored due to suspected apneas. Methods: Cross-sectional study. Patients aged <3 months hospitalized from 2011 to 2023 were included. All were referred for suspected apneas, and cardiorespiratory polygraphies (PG) were conducted simultaneous to non-invasive monitoring. Demographic, PG, and diagnostic variables were recorded. PG values were obtained and compared between diagnostic groups. Association was evaluated according to diagnosis, prematurity, presence, and alteration type with Kruskal–Wallis, Wilcoxon, and Fisher tests. Association between quantitative variables was assessed with Spearman’s rho and the presence of alteration with binomial logistic regression. Analysis was performed with Jamovi v.2.3, and statistical significance was defined as p < 0.05. Results: A total of 155 studies were included. Median age was 41.0 days (IQR 22.0–59.0), median gestational age was 38 weeks (IQR 32.0–42.0), and 52.3% were premature. Diagnosis: brief resolved unexplained events (BRUE) (58.1%), apnea of prematurity (27.1%), hypotonic syndrome (7.1%), laryngomalacia (LGM) (3.9%), and craniofacial alterations (CFA) (3.9%). Altered results in 21.9% polygraphies: 44.1% with AHI ≧ 5/h and 20.6% with SpO2 ≦ 90% in >5% of the record. CFA and LGM patients had a higher risk of an altered polygraph than those with apnea of prematurity (OR 21.3/8.5) and BRUE (OR 35.9/14.3), respectively. Conclusions: Infants under three months of age referred for apnea showed often abnormal polygraphic indices, showing significant differences between diagnostic groups. Performance of sleep studies in these groups was feasible and allowed to confirm the presence of apneas and their level of severity. Particular attention should be considered in children with CFA and LMG, since their risk is significantly higher. Age-specific apnea patterns seem to be of interest, as this may possibly lead to future consequences.
Full article
(This article belongs to the Special Issue The Circadian Rhythm Research in Infants and Young Children)
►▼
Show Figures

Figure 1
Open AccessReview
Appropriate Lifelong Circadian Rhythms Are Established During Infancy: A Narrative Review
by
Teruhisa Miike
Clocks & Sleep 2025, 7(3), 41; https://doi.org/10.3390/clockssleep7030041 - 7 Aug 2025
Abstract
In humans, the master circadian clock, present in the suprachiasmatic nucleus, plays an important role in controlling life-sustaining functions. The development of the circadian clock begins in the fetal period and is almost completed during infancy to early childhood, based on the developmental
[...] Read more.
In humans, the master circadian clock, present in the suprachiasmatic nucleus, plays an important role in controlling life-sustaining functions. The development of the circadian clock begins in the fetal period and is almost completed during infancy to early childhood, based on the developmental program that is influenced by the mother’s daily rhythms and, after birth, with the addition of information from the daily life environment. It is known that circadian rhythms are deeply related not only to the balance of a child’s mental and physical development but also to maintaining mental and physical health throughout one’s life. However, it has been suggested that various health problems in the future at any age may be caused by the occurrence of circadian disturbances transmitted by the mother during the fetal period. This phenomenon can be said to support the so-called DOHaD theory, and the involvement of the mother in the maturation of appropriate and stable circadian rhythms cannot be ignored. We consider the problems and countermeasures during the fetal and infant periods, which are important for the formation of circadian clocks.
Full article
(This article belongs to the Special Issue The Circadian Rhythm Research in Infants and Young Children)
►▼
Show Figures

Figure 1
Open AccessArticle
Who Benefits the Most from Sleep Hygiene Education? Findings from the SLeep Education for Everyone Program (SLEEP)
by
Alyssa Tisdale, Nahyun Kim, Dawn A. Contreras, Elizabeth Williams and Robin M. Tucker
Clocks & Sleep 2025, 7(3), 40; https://doi.org/10.3390/clockssleep7030040 - 1 Aug 2025
Abstract
This study examined data from participants who completed the SLeep Education for Everyone Program (SLEEP) to explore how various demographic variables affected sleep outcomes and to determine which participant characteristics predicted success. A total of 104 individuals participated. The Sleep Hygiene Index (SHI)
[...] Read more.
This study examined data from participants who completed the SLeep Education for Everyone Program (SLEEP) to explore how various demographic variables affected sleep outcomes and to determine which participant characteristics predicted success. A total of 104 individuals participated. The Sleep Hygiene Index (SHI) measured undesirable sleep behaviors; the Pittsburgh Sleep Quality Index (PSQI) assessed sleep quality and self-reported sleep duration. Participant demographic information was collected at baseline. A mixed ANOVA evaluated group differences, and a multiple linear regression model identified predictors of sleep improvements. Change in SHI scores from pre- to post-intervention demonstrated a significant time × group interaction between Black and white participants (p = 0.024); further analysis indicated Black participants improved more. Better baseline scores predicted more favorable post-intervention outcomes for SHI, PSQI, and sleep duration. Fewer chronic conditions predicted better post-intervention SHI and PSQI scores. Older age also predicted better SHI scores. More favorable initial scores, fewer chronic conditions, and older age were the strongest predictors of positive outcomes following SLEEP. Improved sleep hygiene, sleep quality, and sleep duration were observed over time within subjects across all groups. In summary, SLEEP appears to be effective. Further work exploring challenges experienced by younger participants or those with multiple co-morbidities is warranted.
Full article
(This article belongs to the Section Human Basic Research & Neuroimaging)
►▼
Show Figures

Figure 1
Open AccessReview
The Role of Sex in the Impact of Sleep Restriction on Appetite- and Weight-Regulating Hormones in Healthy Adults: A Systematic Review of Human Studies
by
Mira Alfikany, Khaula Sakhr, Stef Kremers, Sami El Khatib, Tanja Adam and Ree Meertens
Clocks & Sleep 2025, 7(3), 39; https://doi.org/10.3390/clockssleep7030039 - 29 Jul 2025
Abstract
Short sleep has been linked to overweight, possibly via alterations in appetite-regulating hormones, but findings are inconsistent. Sex differences may contribute to this variability. This systematic review examines whether sex modifies the hormonal response to sleep curtailment. PubMed, Embase, Cochrane, CINAHL, and PsycINFO
[...] Read more.
Short sleep has been linked to overweight, possibly via alterations in appetite-regulating hormones, but findings are inconsistent. Sex differences may contribute to this variability. This systematic review examines whether sex modifies the hormonal response to sleep curtailment. PubMed, Embase, Cochrane, CINAHL, and PsycINFO were searched for English-language experimental studies published before December 2024. Included studies assessed at least one appetite-regulating hormone and presented sex-specific analyses. Studies involving health conditions affecting sleep, circadian misalignment, or additional interventions were excluded. Risk of bias was assessed using the Revised Cochrane Risk-of-Bias tool (RoB 2). Eight studies (n = 302 participants) met inclusion criteria. A narrative synthesis of the findings was conducted for each hormone separately to explore potential differences in their response to sleep restriction. Some sex-related variations in hormonal response to sleep restriction have been observed for leptin (four studies, n = 232), insulin (three studies, n = 56), glucagon-like peptide-1 (one study, n = 27), ghrelin (three studies, n = 87), adiponectin (two studies, n = 71) and thyroxine (two studies, n = 41). However, findings were inconsistent with no clear patterns. No sex-related differences were found for glucagon or PYY, though data were limited. Findings suggest sex may influence hormonal responses to sleep restriction, but inconsistencies highlight the need to consider factors such as BMI and energy balance. Well-controlled, adequately powered studies are needed to clarify these effects.
Full article
(This article belongs to the Section Human Basic Research & Neuroimaging)
►▼
Show Figures

Figure 1
Open AccessArticle
Uvulopalatopharyngoplasty Versus Expansion Sphincter Pharyngoplasty: A Single Centre Experience
by
Teresa Bernadette Steinbichler, Birte Bender, Roland Hartl, Verena Strasser, Daniel Sontheimer, Sladjana Buricic, Barbara Kofler, Birgit Högl, Herbert Riechelmann and Benedikt Hofauer
Clocks & Sleep 2025, 7(3), 38; https://doi.org/10.3390/clockssleep7030038 - 29 Jul 2025
Abstract
Background: Uvulopalatopharyngoplasty (UPPP) and expansion sphincter pharyngoplasty (ESP) are two standard surgical procedures for the treatment of snoring and obstructive sleep apnea. In a retrospective clinical trial, we compared the two surgical techniques regarding objective sleep parameters and patients’ reported outcomes. Materials and
[...] Read more.
Background: Uvulopalatopharyngoplasty (UPPP) and expansion sphincter pharyngoplasty (ESP) are two standard surgical procedures for the treatment of snoring and obstructive sleep apnea. In a retrospective clinical trial, we compared the two surgical techniques regarding objective sleep parameters and patients’ reported outcomes. Materials and Methods: Patients treated with UPPP or ESP between January 2016 and February 2020 were included in this retrospective clinical trial. Pre- and postoperative AHI, BMI, and smoking habits were recorded. Subjective improvement was assessed by the ESS score and symptom relief reported by patients and their bed partners. Results: Between 2016 and 2020, 114 patients were included in the study, 74 patients suffered from OSA, and 30 patients had non-apnoeic snoring (AHI < 5/h). No preoperative sleeping studies were available in 10 patients (10/114; 9%). Based on the findings during drug-induced sedation endoscopy, most patients received an ESP (71/114, 62%), and 43 patients received a UPPP (43/114, 38%). Additionally, in 52/114 (46%), radio frequency ablation of the tongue base was performed if DISE revealed retrolingual collapse. ESP reduced AHI from 21.1 ± 10.8/h to 13.3 ± 12.1/h (p = 0.04), whereas UPPP caused a non-significant decrease in the AHI from 25.0 ± 13.8/h to 18.2 ± 14.6/h (p = 0.6). A minor secondary bleeding was observed in 32 patients, which was effectively treated with electrocautery or conservative therapy (32/114). This was more common in the ESP group (22/71; 31%) than in the UPPP group (10/43; 23%). Postoperative need for analgesics was higher in the ESP group than in the UPPP group. The ESS score showed no significant improvement after UPPP or ESP (p = 0.3), but subjective improvement in snoring was reported by 87/114 (76%) patients. Conclusion: AHI reduction was significantly higher in the ESP patient group than in the UPPP group. ESP patients had a slightly higher rate of minor secondary bleeding and postoperative need for analgesics than UPPP patients.
Full article
(This article belongs to the Special Issue Emerging Trends in Obstructive Sleep Apnea)
►▼
Show Figures

Figure 1
Open AccessArticle
Deletion of Clock Gene Period 2 (Per2) in Astrocytes Shortens Clock Period but Does Not Affect Light-Mediated Phase Shifts in Mice
by
Soha A. Hassan, Katrin S. Wendrich and Urs Albrecht
Clocks & Sleep 2025, 7(3), 37; https://doi.org/10.3390/clockssleep7030037 - 17 Jul 2025
Abstract
The circadian clock is a self-sustaining oscillator with a period of approximately 24 h, enabling organisms to anticipate daily recurring events, such as sunrise and sunset. Since the circadian period is not exactly 24 h and the environmental day length varies throughout the
[...] Read more.
The circadian clock is a self-sustaining oscillator with a period of approximately 24 h, enabling organisms to anticipate daily recurring events, such as sunrise and sunset. Since the circadian period is not exactly 24 h and the environmental day length varies throughout the year, the clock must be periodically reset to align an organism’s physiology with the natural light/dark cycle. This synchronization, known as entrainment, is primarily regulated by nocturnal light, which can be replicated in laboratory settings using a 15 min light pulse (LP) and by assessing locomotor activity. An LP during the early part of the dark phase delays the onset of locomotor activity, resulting in a phase delay, whereas an LP in the late dark phase advances activity onset, causing a phase advance. The clock gene Period 2 (Per2) plays a key role in this process. To investigate its contributions, we examined the effects of Per2 deletion in neurons versus astrocytes using glia-specific GPer2 (Per2/GfapCre) knockout (KO) and neuronal-specific NPer2KO (Per2/NesCre) mice. All groups were subjected to Aschoff type II protocol, where an LP was applied at ZT14 or ZT22 and the animals were released into constant darkness. As control, no LP was applied. Phase shift, period, amplitude, total activity count, and rhythm instability were assessed. Our findings revealed that mice lacking Per2 in neurons (NPer2) exhibited smaller phase delays and larger phase advances compared to control animals. In contrast, mice with Per2 deletion specifically in glial cells including astrocytes (GPer2) displayed normal clock resetting. Interestingly, the absence of Per2 in either of the cell types resulted in a shorter circadian period compared to control animals. These results suggest that astrocytic Per2 is important for maintaining the circadian period but is not required for phase adaptation to light stimuli.
Full article
(This article belongs to the Section Animal Basic Research)
►▼
Show Figures

Figure 1
Open AccessArticle
Blood Metabolic Biomarkers of Occupational Stress in Healthcare Professionals: Discriminating Burnout Levels and the Impact of Night Shift Work
by
Andreea Petra Ungur, Andreea-Iulia Socaciu, Maria Barsan, Armand Gabriel Rajnoveanu, Razvan Ionut, Carmen Socaciu and Lucia Maria Procopciuc
Clocks & Sleep 2025, 7(3), 36; https://doi.org/10.3390/clockssleep7030036 - 14 Jul 2025
Abstract
Burnout syndrome is characterized mainly by three criteria (emotional exhaustion, depersonalization, and low personal accomplishment), and further exacerbated by night shift work, with profound implications for individual and societal well-being. The Maslach Burnout Inventory survey applied to 97 medical care professionals (with day
[...] Read more.
Burnout syndrome is characterized mainly by three criteria (emotional exhaustion, depersonalization, and low personal accomplishment), and further exacerbated by night shift work, with profound implications for individual and societal well-being. The Maslach Burnout Inventory survey applied to 97 medical care professionals (with day and night work) revealed different scores for these criteria. Blood metabolic profiles were obtained by UHPLC-QTOF-ESI+-MS untargeted metabolomics and multivariate statistics using the Metaboanalyst 6.0 platform. The Partial Least Squares Discrimination scores and VIP values, Random Forest graphs, and Heatmaps, based on 99 identified metabolites, were complemented with Biomarker Analysis (AUC ranking) and Pathway Analysis of metabolic networks. The data obtained reflected the biochemical implications of night shift work and correlated with each criterion’s burnout scores. Four main metabolic pathways with important consequences in burnout were affected, namely lipid metabolism, especially steroid hormone synthesis and cortisol, the energetic mitochondrial metabolism involving acylated carnitines, fatty acids, and phospholipids as well polar metabolites’ metabolism, e.g., catecholamines (noradrenaline, acetyl serotonin), and some amino acids (tryptophan, tyrosine, aspartate, arginine, valine, lysine). These metabolic profiles suggest potential strategies for managing burnout levels in healthcare professionals, based on validated criteria, including night shift work management.
Full article
(This article belongs to the Special Issue New Advances in Shift Work)
►▼
Show Figures

Figure 1
Open AccessArticle
The Owls Are Not What They Seem: Health, Mood, and Sleep Problems Reported by Morning and Evening Types with Atypical Timing of Weekend Sleep
by
Arcady A. Putilov, Evgeniy G. Verevkin, Dmitry S. Sveshnikov, Zarina V. Bakaeva, Elena B. Yakunina, Olga V. Mankaeva, Vladimir I. Torshin, Elena A. Trutneva, Michael M. Lapkin, Zhanna N. Lopatskaya, Roman O. Budkevich, Elena V. Budkevich, Natalya V. Ligun, Alexandra N. Puchkova and Vladimir B. Dorokhov
Clocks & Sleep 2025, 7(3), 35; https://doi.org/10.3390/clockssleep7030035 - 11 Jul 2025
Abstract
Morningness-eveningness is usually assessed as either a trait or a state using either a morning–evening preference scale or sleep timing reported for free days, respectively. These assessments were implemented in numerous studies exploring the associations between morningness-eveningness and health, mood, and sleep problems.
[...] Read more.
Morningness-eveningness is usually assessed as either a trait or a state using either a morning–evening preference scale or sleep timing reported for free days, respectively. These assessments were implemented in numerous studies exploring the associations between morningness-eveningness and health, mood, and sleep problems. Evening types almost always had more problems than morning types. We examined these associations in university students with conflicting results of trait and state assessments of morningness-eveningness and tried to confirm their chronotype using a multidimensional chronotyping approach that recognizes four types other than morning and evening (lethargic, vigilant, napping, and afternoon). The conflicting trait and state assessments of morningness-eveningness were found in 141 of 1582 students. Multidimensional chronotyping supported morningness of morning types with late weekend sleep timing, and the associations with health, mood, and sleep problems resembled the associations of other morning types (i.e., these associations persisted despite late sleep timing). In contrast, evening types with early weekend sleep timing were more likely classified as lethargic or napping types rather than evening types. They did not resemble evening types in their associations with health, mood, and sleep problems (i.e., early sleep timing did not change these associations). Model-based simulations of the sleep–wake cycles of students with conflicting trait and state assessments suggested that their bedtimes cannot be solely determined by their biological clocks. On weekdays or weekends, mind-bedtime procrastination can lead to missing the bedtime signal from their biological clocks (i.e., self-deprivation of sleep or, in other words, voluntary prolongation of the wake phase of the sleep–wake cycle).
Full article
(This article belongs to the Section Computational Models)
►▼
Show Figures

Figure 1
Open AccessArticle
Association Between Dreams, Anxiety, and Depressive Symptoms Among Japanese Adolescents: A Cross-Sectional Study
by
Yuki Tanaka, Yuichiro Otsuka, Suguru Nakajima, Osamu Itani, Tomomi Miyoshi and Yoshitaka Kaneita
Clocks & Sleep 2025, 7(3), 34; https://doi.org/10.3390/clockssleep7030034 - 26 Jun 2025
Abstract
Worsening adolescent mental health is a significant social issue. Although dreams may reflect one’s mental state, few studies have focused on adolescents. Therefore, this study investigated the relationship between dream content and mental health, specifically anxiety disorder and depressive symptoms, among Japanese adolescents.
[...] Read more.
Worsening adolescent mental health is a significant social issue. Although dreams may reflect one’s mental state, few studies have focused on adolescents. Therefore, this study investigated the relationship between dream content and mental health, specifically anxiety disorder and depressive symptoms, among Japanese adolescents. This cross-sectional study obtained data on gender, grade, age, lifestyle habits, weekday sleep duration, anxiety disorder symptoms, depressive symptoms, and dreams from Japanese high school students. The data were analyzed via multiple logistic regression analyses. The prevalence of anxiety and depressive symptoms increased with the frequency of “rumination at bedtime”, “memory of dreams”, “emotional carryover”, and “awakening by frightening”, “unpleasant”, “film-like”, “fantastical”, and “recurring” dreams. However, this was not the case for “pleasant dreams”. Furthermore, “rumination at bedtime” (anxiety disorder symptoms: adjusted odds ratio: 10.60; 95% confidence interval: 5.92–18.97; depressive symptoms: 8.79, 5.58–13.87) and “unpleasant dreams” (anxiety disorder symptoms: 5.25, 2.86–9.64; depressive symptoms: 10.13, 5.57–18.44) exhibited particularly high odds ratios. “Rumination at bedtime” and “unpleasant dreams” may serve as early indicators of declining mental health. School- and parent-led interventions aimed at improving mental well-being may help prevent the progression or exacerbation of anxiety and depressive symptoms among adolescents.
Full article
(This article belongs to the Section Human Basic Research & Neuroimaging)
Open AccessReview
Evaluation of the Circadian Rhythm Component Cipc (Clock-Interacting Pacemaker) in Leukemogenesis: A Literature Review and Bioinformatics Approach
by
Leidivan Sousa da Cunha, Beatriz Maria Dias Nogueira, Flávia Melo Cunha de Pinho Pessoa, Caio Bezerra Machado, Deivide de Sousa Oliveira, Manoel Odorico de Moraes Filho, Maria Elisabete Amaral de Moraes, André Salim Khayat and Caroline Aquino Moreira-Nunes
Clocks & Sleep 2025, 7(3), 33; https://doi.org/10.3390/clockssleep7030033 - 25 Jun 2025
Abstract
Circadian rhythms (CRs) are a key biological system regulating physiological processes such as metabolism, cell growth, DNA repair, and immunity, adapting to environmental changes like the light/dark cycle. Governed by internal clocks, it modulates gene expression through feedback loops involving Clock Genes (CGs),
[...] Read more.
Circadian rhythms (CRs) are a key biological system regulating physiological processes such as metabolism, cell growth, DNA repair, and immunity, adapting to environmental changes like the light/dark cycle. Governed by internal clocks, it modulates gene expression through feedback loops involving Clock Genes (CGs), with the cycle initiated by CLOCK–BMAL1 and NPAS2–BMAL1 heterodimers. Disruptions in circadian rhythms have been linked to diseases including metabolic disorders, neurodegeneration, and cancer. CIPC (CLOCK-interacting pacemaker) has been studied as a negative regulator of the CLOCK–BMAL1 complex, focusing on its role in cancer, particularly leukemias. Public datasets and bioinformatics tools were used to examine CIPC gene expression in healthy patients and acute myeloid leukemia (AML) samples. Our analysis revealed significant overexpression of CIPC in AML compared to healthy tissues (p < 0.0001 ****). Additionally, survival analysis indicated significant differences in overall survival based on CIPC expression, with a log-rank test p-value = 0.014, suggesting that CIPC expression may affect overall patient survival. Altered CIPC expression may contribute to leukemogenesis by inhibiting circadian genes, which are often disrupted in leukemia. Furthermore, CIPC interacts with oncogenic pathways, including the MAPK/ERK pathway, which is essential for cell proliferation. Additional studies are needed to validate these findings and explore the detailed role of CIPC in cancer development.
Full article
(This article belongs to the Section Human Basic Research & Neuroimaging)
►▼
Show Figures

Figure 1
Open AccessArticle
Enhancing Sleep Quality: The Impact of the “Repose Tao” Pillow with Taopatch® Nanotechnology—A Pilot Study
by
Francesca Campoli, Francesca Orofino, Giuseppe Messina, Donatella Di Corrado and Vincenzo Cristian Francavilla
Clocks & Sleep 2025, 7(3), 32; https://doi.org/10.3390/clockssleep7030032 - 24 Jun 2025
Abstract
Background. Sleep disorders are a group of conditions that disrupt normal sleep patterns and are among the most common clinical challenges faced today. An innovative device that employs nanotechnology to deliver beneficial effects on the human body is the Taopatch® (Tao Technologies,
[...] Read more.
Background. Sleep disorders are a group of conditions that disrupt normal sleep patterns and are among the most common clinical challenges faced today. An innovative device that employs nanotechnology to deliver beneficial effects on the human body is the Taopatch® (Tao Technologies, Vedelago, Italy). This study aims to assess the effectiveness of such nanotechnology-based devices in improving sleep quality. Methods. This study included only female participants, as a review of the literature indicated that sleep disorders are more prevalent in women than in men. A total of 30 subjects (with a mean age of 44.8 ± 3.44 years) were randomly divided into two groups: an experimental group and a control group. Sleep quality was evaluated three times throughout the study for each participant using the Pittsburgh Sleep Quality Index (PSQI). The Taopatch® devices were applied using a specialized pillow. Results. The experimental group showed significantly better sleep quality (p < 0.001) compared to the control group. Conclusions. Our findings suggest that the application of the Taopatch® has a positive impact on sleep quality by optimizing posture, aligning the cervical spine, and promoting muscle relaxation. This device uses advanced nanotechnology to enhance various physiological functions, contributing to better overall well-being.
Full article
(This article belongs to the Section Human Basic Research & Neuroimaging)
►▼
Show Figures

Figure 1
Open AccessArticle
Translation and Validation of the Richards–Campbell Sleep Questionnaire for Intensive Care Unit Patients in Morocco: Reliability and Validity Assessment
by
Abdelmajid Lkoul, Keltouma Oum’barek, Mohamed Amine Baba, Asmaa Jniene and Tarek Dendane
Clocks & Sleep 2025, 7(3), 31; https://doi.org/10.3390/clockssleep7030031 - 23 Jun 2025
Cited by 1
Abstract
Introduction: For patients in intensive care units, the Richards–Campbell Sleep Questionnaire (RCSQ) seems to be a useful tool for assessing sleep quality. However, its application in the Moroccan medical context could be limited due to the lack of a dialectal Arabic version for
[...] Read more.
Introduction: For patients in intensive care units, the Richards–Campbell Sleep Questionnaire (RCSQ) seems to be a useful tool for assessing sleep quality. However, its application in the Moroccan medical context could be limited due to the lack of a dialectal Arabic version for Morocco. This study’s objective was to translate and validate the RCSQ into Arabic for Moroccan speakers. Patients and methods: For this investigation, a cross-sectional design was adopted. The RCSQ was translated and validated into Arabic for Morocco in accordance with the recommendations. For every scale, psychometric properties were computed. The Cronbach’s α coefficient was utilized to evaluate the internal consistency of multi-item measures. Results: The study involved 224 patients, whose mean age was 47 ± 18.3 years. The RCSQ’s internal consistency, or Cronbach’s alpha, was computed, and all dimensions showed good reliability over the 0.92 (0.894–0.983) level. The items demonstrated good reliability and validity, with correlation values larger than 0.4, according to the data. Conclusion: The RCSQ translated into Arabic for Morocco appears to have good psychometric qualities, making it useful for assessing the quality of sleep of patients in intensive care units within Moroccan healthcare settings.
Full article
(This article belongs to the Section Society)
►▼
Show Figures

Figure 1
Highly Accessed Articles
Latest Books
E-Mail Alert
News
Topics
Topic in
Brain Sciences, Clocks & Sleep, Neurology International, NeuroSci
Translational Advances in Neurodegenerative Dementias, Second Edition
Topic Editors: Francesco Di Lorenzo, Annibale AntonioniDeadline: 30 September 2026

Conferences
Special Issues
Special Issue in
Clocks & Sleep
New Advances in Shift Work
Guest Editor: Eva SchernhammerDeadline: 30 September 2025
Special Issue in
Clocks & Sleep
Emerging Trends in Obstructive Sleep Apnea
Guest Editor: Ali Albert el-SolhDeadline: 31 October 2025
Special Issue in
Clocks & Sleep
Updates in Narcolepsy and Related Disorders
Guest Editors: Hrayr P. Attarian, Eun Yeon Joo, Bharati PrasadDeadline: 31 December 2025
Topical Collections
Topical Collection in
Clocks & Sleep
Featured Papers from Australasian Chronobiology Society
Collection Editors: Sean Cain, Elise McGlashan