Psychiatry Investig.  2018 May;15(5):520-530. 10.30773/pi.2018.03.17.

Impact of Exposure to Dim Light at Night on Sleep in Female and Comparison with Male Subjects

• Cho CH
• Yoon HK
• Kang SG
• Kim L
• Lee EI
• Lee HJ

• KMID: 2462793
• DOI: http://doi.org/10.30773/pi.2018.03.17

Abstract

OBJECTIVE
Light pollution has become a social and health issue. We performed an experimental study to investigate impact of dim light at night (dLAN) on sleep in female subjects, with measurement of salivary melatonin.
METHODS
The 25 female subjects (Group A: 12; Group B: 13 subjects) underwent a nocturnal polysomnography (NPSG) session with no light (Night 1) followed by an NPSG session randomly assigned to two conditions (Group A: 5; Group B: 10 lux) during a whole night of sleep (Night 2). Salivary melatonin was measured before and after sleep on each night. For further investigation, the female and male subjects of our previous study were collected (48 subjects), and differences according to gender were compared.
RESULTS
dLAN during sleep was significantly associated with decreased total sleep time (TST; F=4.818, p=0.039), sleep efficiency (SE; F=5.072, p=0.034), and Stage R latency (F=4.664, p=0.041) for female subjects, and decreased TST (F=14.971, p<0.001) and SE (F=7.687, p=0.008), and increased wake time after sleep onset (F=6.322, p=0.015) and Stage R (F=5.031, p=0.03), with a night-group interaction (F=4.579, p=0.038) for total sample. However, no significant melatonin changes. There was no significant gender difference of the impact of dLAN on sleep, showing the negative changes in the amount and quality of sleep and the increase in rapid eye movement (REM) sleep in the both gender group under 10 lux condition.
CONCLUSION
We found a negative impact of exposure to dLAN on sleep in female as well as in merged subjects. REM sleep showed a pronounced increase under 10 lux than under 5 lux in merged subjects, suggesting the possibility of subtle influences of dLAN on REM sleep.

Keyword

Dim light at night; Sleep; Polysomnography; Melatonin; REM sleep

MeSH Terms

Female*
Humans
Male*
Melatonin
Polysomnography
Sleep, REM
Melatonin