How the lagged and accumulated effects of stress, coping and task affect mood and fatigue during nurse’s shifts

200 palabras máx, estructurado sin encabezados) Nurses experience significant stress and emotional exhaustion, leading to burnout and fatigue. This study assessed how the nurses’ mood and fatigue evolves during their shifts, and the lagged and accumulated factors that influence these phenomena. A two-level design with repeated measures was applied to a sample of 113 nurses, performing an ecological momentary assessment of different parameters and multilevel longitud ina l two-level modelling of the data. Accordingly, mood appeared to be explained by effort, by the negative lagged effect of reward and by accumulated effort, each following a quadratic trend, and it was influenced by previously executing a direct care task. By contrast, fatigue was explained by the current and lagged effect of effort, by the lagged effect of reward and by accumulated effort, again following quadratic trends. Fatigue was also associated with direct care, and the prior effect of documentation and communica t ion tasks. Mood was also explained by problem-focused and emotion-focused coping strategies, indicative of negative mood, and by support-seeking and refusal coping strategies. Hence, mood and fatigue do not depend on a single factor like workload but rather, on the evolution and distribution of tasks, as well as on the stress during a shift and how it is handled.


Introduction
Nurses are exposed to significant stress at work, which can lead to burnout, provoking a deterioration in the nurses' health, a decrease in the quality of their care and an increase in their intention to quit (Dall'Ora, Griffiths, Hope, Barker, & Smith, 2020;Hasan, 2017; Martí n-Del-Rí o, Solanes-Puchol, Martí nez-Zaragoza, & Benavides-Gil, 2018;Moustaka & Constantinidis, 2010;Yau et al., 2012). Two widely studied models of work stress have been tested in the context of nursing, the Karasek's Demand-Control model (1998)

and
Siegrist's Effort-Reward Imbalance (ERI) model (1996). Thus, nurses suffering high demands or an excessive workload, and with little control or autonomy when carrying out their tasks, tend to present greater health problems (see Baba, Tourigny, Wang, Lituchy, & Monserrat, 2013;Magnago, Lisboa, Griep, Zeitoune, & Tavares, 2010;Negussie & Kaur, 2016). In addition, the lack of balance between the effort made at work and the rewards obtained (i.e. recognition, salary and opportunities for promotion) would also generate a greater risk of burnout in the medium and long-term, and greater vulnerability to different pathologies (see Caruso, 2014;Hasselhorn, Tackenberg, & Peter, 2004;Padilla & Palmeiro-Silva, 2017;Schreuder, Roelen, Koopmans, Moen, & Groothoff, 2010). By combining both of the aforementioned models, in tasks and situations that involve high levels of demand/effort with low levels of control/reward, negative mood increases significantly. However, if the level of control/reward was high, then mood remained positive, even if the degree of demand/effort was high (Johnston, Jones, Charles, McCann & McKee, 2013).
Fatigue is considered to be an effect of work stress along with emotional exhaustio n (Hockey, 2013). Some of the consequences of fatigue are lapses in attention and the inability to stay focused, compromised problem solving, confusion, memory lapses, impaired communication, increased reaction time and slowed or faulty informa tio n processing and judgment. In addition, fatigue produces negative effects on mood, such as irritability, indifference and lack of empathy (The Joint Commission, 2011). In a classic study, key elements that define fatigue are time, the task involved and stress (Cameron, 1973). Moreover, fatigue has been related to excess effort and a lack of reward (Wylie, Genova, Deluca & Dobryakova, 2017).
In terms of nursing, demands that predict fatigue and control or autonomy have an absorbing effect on fatigue (Rahman, Abdul-Mumin & Naing, 2016). Moreover, it has been proposed that nursing tasks are less rewarding and that mood was worse when exhaustion or fatigue were detected (Ferná ndez-Castro et al., 2017). In summary, there is considerable evidence that fatigue and emotional exhaustion are both consequences of work stress in nurses.
Passage of time effects are evident in healthcare contexts, with a decrease in the effectiveness of clinical decision making as the working day progresses and over multip le work shifts (Allan et al., 2019;Thompson, 2019). In addition, the effort associated with long and continuous work shifts provokes high levels of fatigue in nurses, which negatively influences their performance and patient safety (Rogers, 2008;Smith-Miller, Shaw-Kokot, Curro, & Jones, 2014;Thompson, Stock, & Banuelas, 2016). Variations in the mood of nurses have also been observed between the beginning and end of each shift (Bueno, Figueiredo, & Figueiredo, 2003;De Martino & Misko, 2004). Significantly, attempts have been made to predict the levels of fatigue from the values of physical energy expended, as well as the demand, control and reward accumulated in the previous 90 minutes, through ecological momentary assessment throughout the nurse's work shift (Johnston et al., 2018). Accordingly, fatigue did not necessarily depend on the physical energy expended or on the perceived demands but rather, on the perceived control over their work and the rewards associated with the work-related stress.
Mood and fatigue were previously seen to be influenced by the perceived effort, reward, demand and control, as well as by the specific task that nurses have to perform and the type of coping that is carried out in relation to each task (Ferná ndez-Castro et al., 2017).
Mood was seen to significantly deteriorate in association with tasks and situations that involved high levels of demand/effort and low levels of control/reward (Johnston et al., 2013), whereas mood remained positive when the level of control/reward was high, even when the degree of demand/effort was also high. However, nurses must perform differe nt tasks in their work and not all of them have the same implications or are perceived in the same way. In this regard, physically demanding patient care tasks, logistic/management/organization tasks and multitasking demands, are those that appear to contribute to fatigue most frequently (Steege, Drake, Olivas and Mazza, 2015;Steege and Dykstra, 2016).
Likewise, not all coping strategies work in the same way in all situations and/or for all people, such that the risk of physical and psychological pathologies, increases with the use of maladaptive coping strategies, including burnout (Chang, Bidewell, Huntingto n, Daly, & Johnson, 2007;Hä tinen, Mä kikangas, Kinnunen, & Pekkonen, 2013;Lazarus & Folkman, 1984;Nayomi, 2016;Rothbaum, Weisz, & Snyder, 1982;Yoshizawa et al., 2016). Whilst problem-focused coping behaviours are not associated with fatigue in nurses, avoidance coping like drinking alcohol, avoiding situations or blocking emotions appear to predict fatigue (Samaha, Lal, Samaha and Wyndham, 2007). Moreover, the use of avoidance coping and the perception of excessive demands on nurses are thought to be important predictors of mood disturbances (Healy and McKay, 2000). Indeed, an important challenge in the stress research is to understand how stress, coping and health changes in individuals over time (Segerstrom and O'Connor, 2012), with insuffic ie nt progress in this field to date.
Hence, it remains unclear if the mood and fatigue of nurses during their shifts are determined by a delayed and accumulated effect of: performing certain specific tasks; the perception of demand; the control, effort and reward related to each of the activities they carry out; and the type of coping strategies used when performing them.

Aim/Research questions
The initial aim of this study was to examine the relationship between stress, mood and fatigue in nurses. A recent study concluded that fatigue does not depend on the demands or on the energy expended but rather, on the perceived control and its associated reward (Johnston et al., 2019). Thus, it remains unclear if previous (lagged effect) or accumulated stress (demand/control, effort/reward) influences the mood and fatigue of nurses. Thus, we hypothesized that: 1. Accumulated effort will worsen mood and will increase fatigue, while reward will produce the opposite effect, as predicted by Siegrist's model.
The second aim was to study the effect of coping on mood and fatigue. It has been shown that higher mean scores in problem-solving, avoidance and seeking social support were associated with higher levels of compassion fatigue (Al Barmawi et al., 2019). Thus, the question remains as to whether the coping strategy previously used or accumulated over time affects the mood and fatigue of nurses. Hence, we hypothesized that: 2. The use of problem-focused and seeking-support strategies will have a delayed and accumulated effect on mood and fatigue, producing a improvement in both; and 3. The use of emotion-focused and refusal strategies will have a delayed and accumulated effect on mood and fatigue, worsening them.
The third aim of this study was to examine the effect of the task on mood and fatigue. It has been shown that physically demanding patient care tasks most frequently produced physical and mental fatigue in nurses (Steege et al., 2015). Thus, the question arises as to whether the previous task or those accumulated over time affect the mood and fatigue of nurses. Accordingly, we hypothesized that: 4. Accumulated direct care tasks improve mood and increase fatigue; 5. Administrative and organizational tasks will have a delayed and negative effect on mood, presumably due to tedium.

Design
Within person and between person relationships were identified by multilevel statistica l analyses. A two-level design with repeated measures was used (Ato, López, & Benavente, 2013) in which the level-1 is established from the moments at which the outcome variables were measured. In level-2 the moments were nested at the person level.

Participants and procedure
A random sample of 113 nurses was recruited from the following wards at two Univers ity hospitals, selecting 80% of the nurses on each ward: internal medicine, surgery, traumatology, oncology, cardiology, neurology, nephrology, pneumology, rheumatolo gy, digestive, gynaecology, geriatrics, palliative care, paediatrics, and psychiatry. Critical care services and emergency services were excluded from the cohort due to the distinctive tasks involved. The nurse-patient ratio ranged from 10 patients in the day shift to 30 patients in the night shift. Of the nurses recruited, 17 finally refused to participate in the study and thus, the final sample was 96 nurses with a response rate of 85.47%.

Ethics
All the nurses participating in the study provided their informed consent, and they were aware that they could leave the study at any moment. Approval was granted by the CEIC (Ethics and Clinical Research Committee) at the University Hospital of Elche (Spain) and at the Hospital of Terrassa (Spain).

Ecological Momentary Assessment
A Samsung Galaxy Mini Smartphone with an Android operating system was especially developed for this study and used to obtain measurements. Data entry was prompted by vibration or a buzzing alarm and if busy, the nurse could postpone the response for 10 minutes. This meant that in terms of hygiene, if the task they were involved in was direct care, it could be completed and the nurses could wash their hands before touching the screen. However, if the question remained unanswered for 20 min then this moment was registered as missing data. Answers were presented on analogue scales and the participants were given 'tips' as to how to select their responses to the questions. The software was designed with a menu the help answer any queries by just touching the screen. The measurements taken at each evaluation point are listed below.
Demand, effort, control, reward. Four questions were designed to appraise the differe nt aspects of work stress: demand, control (labelled as autonomy and skills development), effort, and reward. Each question labelled the term to be evaluated and was followed by a simple question as to how far each concept could be applied to the characteristics of the task being performed at the time. The four questions were answered using a visual analogue scale from 0 to 10 in order to evaluate the intensity of the response, one of the most usual response formats for single-item questions (Patrician, 2004).
Momentary coping. A 10-item coping questionnaire was designed ad-hoc to assess nursing coping in an Ecological Momentary Assessment context (MoCoping: Rovira, Ferrer, Edo, Ferná ndez-Castro, Benavides, Doval, & Martí nez-Zaragoza, 2016) and based on the COPE Inventory (Carver, Scheier, & Weintraub, 1989;Crespo & Cruzado, 1997). The questionnaire followed a structure of one item for each strategy, grouped into four types: a problem-focused approach (including one item of active coping and one of planning); an emotion-focused approach (including one item of acceptance, one of reinterpretation and one of distraction); support-seeking (including one item of emotiona l support and one of instrumental support); and a refusal approach (including one item of denial, one of venting and one of self-blame). The variables were coded as binary, i.e.: the coping strategy was used or not. and other. The variables were coded as binary: i.e. they are undertaking the task or not.
Mood. Mood was measured on a single-item, five-point visual analogue scale, from a happy face to a sad face, where higher values reflect poor mood (see Figure 1).
Fatigue. Fatigue was measured by a single-item, five-point visual analogue scale from a full battery to an empty battery, where higher values mean more intense fatigue (see The order of each record at the person level (level 1, moment) was automatically recorded by the device, registering a mean of five records per shift (every half an hour).

Level 2 Measures (person) Questionnaires
Ad-hoc questionnaire. We recorded the work shift, gender, age, marital status, number of children, years of experience and professional status of the subjects.

Data analyses
No missing data imputation was done and descriptive statistics were obtained using the R Statistical Package (R Core Team, 2020).

Multilevel Modelling (MLM)
Multilevel analysis allows to control for the variance associated with random factors without data aggregation. As fixed effects, we entered the moment of time, demandcontrol and effort-reward, four different types of coping strategies for momentary use, nursing tasks, and mood and fatigue into the model. As random effects, we tested random intercepts and slopes for the effect of the same variables, allowing these to be varied randomly across groups. P-values were obtained by likelihood ratio tests of the full model with the effect in question compared against the model without the effect in question. Zvalues were obtained to test the significance for fixed effects (estimates and standard error data in the tables). Trends of the longitudinal data were studied by testing the linearity of the model for all the outcomes.

Assumptions
Visual inspection of q-q plots using the car R package (Fox & Weisberg, 2011) did not reveal any obvious deviations from homoscedasticity or normality in the dependent variables. The momentary coping strategies were categorized and coded as dummy variables (logit models), with mood and fatigue as quantitative variables.

Initial models, model fit and fit criteria
Model comparison was achieved following the guidelines set out by Bliese and Ployhart (2002) and Bliese (2016), beginning the process by examining the nature of the outcome.
To test the significance of person effects, we carried out a likelihood ratio test comparing the null multilevel model (unconditional model) with a null single-level model, thereby testing the null hypothesis that there were no group differences. Subsequently, the intraclass correlation coefficient (ICC) was estimated in order to calculate the between/within variation ratio. The model's fit was assessed using chi-squared tests on the log-likelihood values to compare the different models, and using the Akaike's information criterion (AIC: Akaike, 1974), a relative goodness of fit index. According to the change in these fitness indices, the last model with significant changes was chosen for each analysis.
The data were analysed using the R Statistical Package (R Core Team, 2020). The lme4 R package (Bates, Mä chler, Bolker, & Walker, 2015) was used to analyse the quantitative outcomes variables, and to obtain a multilevel longitudinal growth curve model of the relationship between stress (demand/control, effort/reward), coping strategies (momentary), tasks, and mood and fatigue. Linearity trends were also analysed by studying the quadratic and cubic trends, and interactions between time and predictors were examined. The P-values of the lme4 outputs were obtained with the lmerTest package (Kuznetsova, Per Bruun Brockhoff, & Christensen, 2016), the ICC was calculated using the sjstats package (Lü decke, 2018) and graphic data processing was done with the ggplot2 (Wickham, 2016) R package.

Mood and fatigue from lagged and current values of the predictors
To predict the lagged effects on mood and fatigue, the lag-1 measures of the predictors were calculated (i.e.: the measures taken in the moment immediately prior to the outcome measure). The current and lagged effects of the predictors were included in a two-level model with the observations over time nested into participants. These analyses were divided into three parts depending on the type of predictors used: stress, coping, or task.
Each analysis was performed separately with each dependent variable, such that six analyses were performed to study the lagged effects. The predictors included were; stress (first analysis)intercept, time and current and lag-1 measures of demand, control, effort and reward; coping (second analysis) intercept, time, and current and lag-1 measures of problem-focused, emotion-focused, support-seeking and avoidance; task (third analys is) intercept, time, and current and lag-1 measures of direct-care, indirect care, medicatio n, documentation, social and communication. Intercept and time were allowed to vary randomly, while the rest of variables were considered as fixed effects.

Mood and fatigue from accumulated values of the predictors
Accumulated values were calculated by summing the previous values of the variable at each time point within each shift. The analyses were again divided into three parts, depending on the type of the predictors used: stress, coping, and task. Each analysis was performed separately with each dependent variable, such that six analyses were used to study the accumulated effects. The effects of the predictors were included in a two-level model with the time of observation nested into participants. The predictors included were: stress (first analysis)intercept, time, and accumulated demand, control, effort and reward; coping (second analysis) intercept, time and accumulated problem-focused, emotion-focused, support-seeking and refusal coping; task (third analysis) intercept, time and accumulated direct-care, indirect care, medication, documentation, social and communication. Intercept and time were allowed to vary randomly, while the remaining variables were considered as fixed effects.

Sample description
In the cohort of nurses studied, 89.90% were female with a mean age of 40.22 years (SD = 8.50). In terms of the shift patterns, 45.45% worked rotating shifts and the remainder worked fixed shiftseither mornings, evenings or nights. Moreover, 5.20% of the nurses had an additional job. The distribution between the two hospitals was 47.42%/52.58% and the mean number of years the nurses had been working at their current job was 9.86 (SD = 7.99), with a mean of 17.40 years experience as a nurse (SD = 8.36). Tenured staff made up 77.31% of the sample and 52.53% had a specialty in nursing beyond their university degree. In addition, 50.51% were in a relationship, 16.16% were single and the remaining were separated, divorced or widowed. In terms of the coping strategies used, problem-focused coping was used in 46.23% of the moments measured, emotion-foc used in 44.89%, support-seeking in 8.13%, and avoidance in 2.70%.

Data analyses
Initially, the effects of the work shift on the dependent variables were described prior to testing the hypotheses, and the data were analysed to see if there were any interactio n effects between work shift and the time into the shift when fatigue can be predicted (see Johnston et al., 2019). Mood was explained by the effect of time (E = 0.09, p < .01) and its interaction with work shift was only marginal (E = 0.07, p = .07 for evening work shift, and E = 0.07, p = .09 for night work shift), displaying a linear trend with an ICC = .37.
Fatigue was explained by the effect of time (E = 2.36e-01, p < .000) and its interactio n with the work shift (E = 9.83e-02, p < .01 for evening work shift, and E = 1.30e-01, p < .01 for night work shift), again with a linear trend and an ICC = .42.
The evolution of mood and fatigue during the work shift was assessed and negative mood increased gradually as the work shift progressed, with slightly higher values for evening and night shifts (Figure 2). In the case of fatigue, the values were again higher for evening and night work shifts, yet with the peculiarity that they increased from moment 4 to 5 (the end of the shift), although this remained stable at these two moments of the shifts in the morning and rotatory shifts. The data from the final models of all 12 of the fitted models was organized in terms of the dependent variable and type of predictor (Table 1). The ICC of the fitted models is close to .50, indicating that the moment (level 1) and person (level 2) exert a similar influence. Significant effects of time were found in all the models and there were significant fixed effects of time in all cases. Hence, negative mood and fatigue increased with time into the shift for all the predictors studied. The effects of all the variables depended on the person (see models of random effects). INSERT

Aim 1: Does previous or accumulated stress (demand/control, effort/reward) influence the mood and fatigue of nurses?
Mood can be explained by the current effort and by the negative lagged effect of reward, following a convex, quadratic trend (Table 1, first section and Figure 3, first spaghetti plot), indicating that mood is more positive when there was a previous reward. The reward experienced previously was effective in reducing negative mood up to a certain extent, after which it remained stable. When stress accumulated, mood was explained by the accumulated effort according to a concave, quadratic trend (Table 1, first section and Mood was explained by problem-focused and emotion-focused coping, and the use of these strategies indicated negative mood. When the effect was accumulated, mood was explained by emotion-focused and refusal coping strategies (Table 1, second section).
Fatigue was explained by previous problem-focused coping, and by emotion-focused and refusal coping. When the effect was accumulated, fatigue was predicted by the four coping strategies assessed: problem-focused, emotion-focused, seeking support (negative), and refusal (Table 1, second section). Hence, the only coping strategy that diminished fatigue was the accumulated use of seeking support.

Aim 3: Does the task previously carried out or accumulated over time influence the mood and fatigue of nurses?
Mood was explained by the effect of executing a previous direct care task and in terms of an accumulated effect, only the documentation task explains mood, albeit negative ly (Table 1, third section). Hence, being occupied with a documentation task for some time improved mood. Fatigue was explained by the effect of the direct care task, and by the prior effect of documentation and communication tasks: both in a negative sense whereby the person involved previously in these tasks experiences less fatigue in the following moment measured. When the effect was accumulated, fatigue was explained by direct care and medication tasks (Table 1, third section).

Discussion
This study set out to examine the variables related to fatigue and mood in nurses in terms of the effects of their work shifts. The effects of the variables were analysed as each shift evolves and this time analysis was especially relevant in the work of nurses, which is mostly carried out in response to demand. The role that these variables play in the longterm development of burnout is also important. In the first place, this study confirms that the effect of the work shift on fatigue depends on the time into the shift. As such, the evening and night shifts as opposed to the morning and rotatory shifts, seem to provoke more fatigue than the other work shifts when approaching the last third of the shift, results that are in line with earlier findings (Johnston et al., 2019).

The effect of stress on mood and fatigue
While the first hypothesis was confirmed, the relationship detected was not lineal and the effect of stress on mood was to a large extent predicted by the Siegrist model (Siegrist, 1996). When current effort is assessed when no previous reward was evident, mood is more negative. However, only accumulated effort produces negative mood. These relationships are not lineal and their effect only persists to the point where no more negative mood is produced despite increasing effort. The effect of stress on fatigue was predicted with precision by the Siegrist model. When prior or current effort increases and reward diminishes, fatigue increases. If effort and reward accumulate, the behaviour of these variables persists up to a given point, at which more effort or less reward does not produce more fatigue. Therefore, the effort during the first few hours of the shift serve as a "warm-up", making it important to reduce fatigue later.

Effect of coping on mood and fatigue
The second hypothesis was not confirmed, as only the effect of seeking support reduced fatigue. The first impression regarding coping is that the data do not agree with the extensive literature indicating that active strategies are more adaptive than passive ones (Jimé nez-Torres, Martí nez, Miró, & Sá nchez, 2012;Shin et al., 2014). This discrepancy is undoubtedly due to how this was assessed in this study. The general style trend of coping was not recorded but rather, how each situation was coped with at the time it occurred, and the nurses could answer that they had not coped in any specific way. As such, it is not strange that mood and fatigue are worse after stressful situations that were coped with in a specific manner. Thus, this study offers evidence of a delayed effect of these coping styles. If we examine mood, we see that coping based on the problem has a delayed effect, whereby if you have had to cope with a problem it continues to have an influence for some time later, even though repeatedly facing a problem does not have a negative effect. Alternatively, the search for social support has no positive or negative effect on subsequent mood.
In terms of fatigue, we see that situations that need to be addressed increase fatigue, although the search for social support, when repeated, reduces fatigue. Thus, an important means to control fatigue is to broaden and improve the social support networks between professionals on the ward and in the hospital. Social support is not only offered by coworkers (Knupp, Patterson, Ford, Zurmehly and Patrick, 2018), yet the support from the nurse's manager was significantly associated with their self-perception of fatigue.
In general terms, the third hypothesis is confirmed, since the use of emotion-focused and refusal strategies worsens the mood and increases fatigue. However, while refusal had cumulative effects it had no delayed effects. Hence, rejecting a stressful situation is not related to being in a worse situatio n a little time later, after it has been avoided, yet rather its repetition enhances negative mood. Therefore, problem-based coping has an opposite effect to that of the refusal, and while in the short term it can decrease well-being and it may be implemented without negative consequences, refusal instigates short-term wellbeing but it is not a resort used repeatedly.

Effect of nursing task on their mood and fatigue
The fourth hypothesis was confirmed only in part, as direct care tasks worsen mood (in contrast to the expected effect) and they produce more fatigue. When engaged previously in a direct care task, the nurses' mood becomes more negative, even though direct care tasks are generally reported by most nurses as very core-professional tasks. It might also have been of interest to know if the direct care task undertaken had or had not been finished by the nurse at the time of reporting (Gabriel, Diefendorff, & Erickson, 2011 Drach-Zahavy, 2019). For nurses, satisfaction in daily task accomplishment is negative ly associated with changes in negative affect at the end of the shift. Moreover, the impact of task accomplishment satisfaction on changes in daily affect is larger for direct care nursing tasks than for the rest of nursing tasks (Gabriel et al., 2011). Thus, having the feeling at the end of the shift of unfinished nursing care when the majority of the tasks have been of direct care would be the circumstance producing the strongest negative affect. However, direct care tasks have a negative delayed effect on mood but not a cumulative effect. This may reflect that it is worse to alternate direct care tasks with other types of tasks than to be able to focus on the demands of direct care. As for mood, direct care produces delayed effects on fatigue. However, both direct care and medication have affect fatigue, which does not occur with mood. Therefore, concentrating on a task when alternating with others can help improve mood at the cost of increasing fatigue.
The fifth hypothesis was not confirmed, as administrative and organizational tasks like documentation or communication seem to improve fatigue, and when documentatio n tasks accumulate, mood is more positive. Documentation or communication are apparently unpleasant tasks for nurses and they are considered best undertaken when they are not very tired. Communication with other healthcare professionals is often considered a complicated task yet it appears to be a more relaxing task that produces positive mood.

Limitations and perspective for future studies
Perhaps the main limitation of this study is that the results and conclusions are only generalizable to ward nurses working in hospitals. Other tasks performed by differe nt types of nurses may differ in terms of the effects of the different coping strategies used.
Future studies should also focus on mechanisms of recovery from fatigue and from negative mood, such as resting and sleep.

Conclusions
These results of this study indicate that mood and fatigue do not depend on a single factor, such as workload but rather, on the distribution and evolution of tasks throughout the shift, the stress they cause and how it is coped with. These data show the need to plan the tasks within a shift to avoid unfinished or delayed care during the shift, and to minimize accumulated negative effects. In addition, the introduction of facilities for routine social support, both by co-workers and supervisors, is also important to prevent burnout.