The Acute Effects of Intermittent Light Exposure in the Evening on Alertness and Subsequent Sleep Architecture
by
Minqi Yang 1,2, Ning Ma 1,3,†, Yingying Zhu 1,†, Ying-Chu Su 2, Qingwei Chen 1
, Fan-Chi Hsiao 2, Yanran Ji 1, Chien-Ming Yang 2,4,* and Guofu Zhou 1,5,6,*
Minqi Yang 1,2, Ning Ma 1,3,†, Yingying Zhu 1,†, Ying-Chu Su 2, Qingwei Chen 1, Fan-Chi Hsiao 2, Yanran Ji 1, Chien-Ming Yang 2,4,* and Guofu Zhou 1,5,6,*
1
School of Psychology, South China Normal University, Guangzhou 510631, China
2
Department of Psychology, National Chengchi University, Taipei 11605, Taiwan
3
Center for Studies of Psychological Application, Guangdong Key Laboratory of Mental Health and Cognitive Science, South China Normal University, Guangzhou 510631, China
4
The Research Center for Mind, Brain and Learning, National Chengchi University, Taipei 11605, Taiwan
5
National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou 510006, China
6
Shenzhen Guohua Optoelectronics Tech. Co., Ltd., Shenzhen 518110, China
*
Authors to whom correspondence should be addressed.
†
The authors contributed equally to this work.
Int. J. Environ. Res. Public Health 2018, 15(3), 524; https://doi.org/10.3390/ijerph15030524
Received: 22 January 2018 / Revised: 28 February 2018 / Accepted: 13 March 2018 / Published: 15 March 2018
(This article belongs to the Special Issue Sleep Health)
Exposure to bright light is typically intermittent in our daily life. However, the acute effects of intermittent light on alertness and sleep have seldom been explored. To investigate this issue, we employed within-subject design and compared the effects of three light conditions: intermittent bright light (30-min pulse of blue-enriched bright light (~1000 lux, ~6000 K) alternating with 30-min dim normal light (~5 lux, ~3600 K) three times); continuous bright light; and continuous dim light on subjective and objective alertness and subsequent sleep structure. Each light exposure was conducted during the three hours before bedtime. Fifteen healthy volunteers (20 ± 3.4 years; seven males) were scheduled to stay in the sleep laboratory for four separated nights (one for adaptation and the others for the light exposures) with a period of at least one week between nights. The results showed that when compared with dim light, both intermittent light and continuous bright light significantly increased subjective alertness and decreased sleep efficiency (SE) and total sleep time (TST). Intermittent light significantly increased objective alertness than dim light did during the second half of the light-exposure period. Our results suggested that intermittent light was as effective as continuous bright light in their acute effects in enhancing subjective and objective alertness and in negatively impacting subsequent sleep.
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Keywords:
acute effects; intermittent light; continuous light; dim light; alertness; sleep structure
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MDPI and ACS Style
Yang, M.; Ma, N.; Zhu, Y.; Su, Y.-C.; Chen, Q.; Hsiao, F.-C.; Ji, Y.; Yang, C.-M.; Zhou, G. The Acute Effects of Intermittent Light Exposure in the Evening on Alertness and Subsequent Sleep Architecture. Int. J. Environ. Res. Public Health 2018, 15, 524.
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