Poor sleep is becoming increasingly prevalent and is associated with adverse health outcomes. Sunlight exposure may improve sleep by regulating circadian rhythms, increasing vitamin D, and influencing melatonin production. However, research on the sunlight-sleep association is limited, especially outside of cross-sectional designs. This study examined associations between daily self-reported sunlight exposure and next-night sleep quality in 103 adults for up to 70 days. The timing of sunlight exposure predicted next-night sleep quality. Specifically, morning sunlight exposure, relative to no sunlight, predicted better sleep quality based on responses to the brief Pittsburg Sleep Quality Index. Duration of sunlight exposure was generally not associated with sleep quality. Morning sunlight may regulate circadian rhythms, subsequently improving sleep. Findings have potential implications for sleep interventions and daylight savings time policies. Future research should test whether morning sunlight exposure can enhance the effectiveness of sleep interventions.
AbboudM (2022) Vitamin D supplementation and sleep: A systematic review and meta-analysis of intervention studies. Nutrients14(5): 1076.
2.
AlessiCAMartinJLWebberAP, et al. (2005) Randomized, controlled trial of a nonpharmacological intervention to improve abnormal sleep/wake patterns in nursing home residents. Journal of the American Geriatrics Society53(5): 803–810.
3.
AndersonARFowersBJ (2020) Lifestyle behaviors, psychological distress, and well-being: A daily diary study. Social Science & Medicine263: 113263.
4.
BeckerNBJesusSNJoãoKADR, et al. (2017) Depression and sleep quality in older adults: A meta-analysis. Psychology, Health & Medicine22(8): 889–895.
5.
BlumeCGarbazzaCSpitschanM (2019) Effects of light on human circadian rhythms, sleep and mood. Somnologie23(3): 147–156.
6.
BoubekriMCheungINReidKJ, et al. (2014) Impact of windows and daylight exposure on overall health and sleep quality of office workers: A case-control pilot study. Journal of Clinical Sleep Medicine10(6): 603–611.
7.
BoutinJAKennawayDJJockersR (2023) Melatonin: Facts, extrapolations and clinical trials. Biomolecules13(6): 943.
8.
BrzezinskiARaiSPurohitA, et al. (2021) Melatonin, clock genes, and mammalian reproduction: What is the link?International Journal of Molecular Sciences22(24): 13240.
9.
BuysseDJReynoldsCFMonkTH, et al. (1989) The Pittsburgh sleep quality index: A new instrument for psychiatric practice and research. Psychiatry Research28(2): 193–213.
10.
ChoYRyuS-HLeeBR, et al. (2015) Effects of artificial light at night on human health: A literature review of observational and experimental studies applied to exposure assessment. Chronobiology International32(9): 1294–1310.
11.
ChoiJHLeeBLeeJY, et al. (2020) Relationship between sleep duration, sun exposure, and serum 25-Hydroxyvitamin D status: A cross-sectional study. Scientific Reports10(1): 4168.
12.
CrowleySJEastmanCI (2015) Phase advancing human circadian rhythms with morning bright light, afternoon melatonin, and gradually shifted sleep: Can we reduce morning bright-light duration?Sleep Medicine16(2): 288–297.
13.
de Alcantara BorbaDReisRSde Melo LimaPHT, et al. (2020) How many days are needed for a reliable assessment by the Sleep Diary?Sleep Science13(1): 49–53.
14.
de Menezes-JúniorLAAde MouraSSMirandaAG, et al. (2023) The mediating role of sun exposure on the association between sedentary behavior and sleep quality: A population-based cross-sectional study. Sleep Medicine108: 98–99.
15.
DüzgünGDurmaz AkyolA (2017) Effect of natural sunlight on sleep problems and sleep quality of the elderly staying in the nursing home. Holistic Nursing Practice31(5): 295.
16.
FigueiroMGSteversonBHeerwagenJ, et al. (2017) The impact of daytime light exposures on sleep and mood in office workers. Sleep Health3(3): 204–215.
17.
ForrestKYZStuhldreherWL (2011) Prevalence and correlates of vitamin D deficiency in US adults. Nutrition Research31(1): 48–54.
18.
FritzJVoPhamTWrightKP, et al. (2020) A chronobiological evaluation of the acute effects of daylight saving time on traffic accident risk. Current Biology30(4): 729–735.e2.
19.
GardaniMBradfordDRRRussellK, et al. (2022) A systematic review and meta-analysis of poor sleep, insomnia symptoms and stress in undergraduate students. Sleep Medicine Reviews61: 101565.
20.
GradisarMDohntHGardnerG, et al. (2011) A randomized controlled trial of cognitive-behavior therapy plus bright light therapy for adolescent delayed sleep phase disorder. Sleep34(12): 1671–1680.
21.
HaleLEmanueleEJamesS (2015) Recent updates in the social and environmental determinants of sleep health. Current Sleep Medicine Reports1(4): 212–217.
22.
HartigTMitchellRde VriesS, et al. (2014) Nature and health. Annual Review of Public Health35(1): 207–228.
23.
IrishLAKlineCEGunnHE, et al. (2015) The role of sleep hygiene in promoting public health: A review of empirical evidence. Sleep Medicine Reviews22: 23–36.
24.
ItaniOJikeMWatanabeN, et al. (2017) Short sleep duration and health outcomes: A systematic review, meta-analysis, and meta-regression. Sleep Medicine32: 246–256.
25.
KerkhofGA (2017) Epidemiology of sleep and sleep disorders in The Netherlands. Sleep Medicine30: 229–239.
26.
KollerM (2016) Robustlmm: An R package for robust estimation of linear mixed-effects models. Journal of Statistical Software75(6): 1–24.
27.
KuhnEMillerKEPuranD, et al. (2022) A pilot randomized controlled trial of the insomnia coach mobile app to assess its feasibility, acceptability, and potential efficacy. Behavior Therapy53(3): 440–457.
28.
LaiMHC (2021) Composite reliability of multilevel data: It’s about observed scores and construct meanings. Psychological Methods26(1): 90–102.
29.
LarsonLRSzczytkoRBowersEP, et al. (2019) Outdoor time, screen time, and connection to nature: Troubling trends among rural youth?Environment and Behavior51(8): 966–991.
30.
MatuschekHKlieglRVasishthS, et al. (2017) Balancing Type I error and power in linear mixed models. Journal of Memory and Language94: 305–315.
31.
MoonEPartonenTBeaulieuS, et al. (2022) Melatonergic agents influence the sleep-wake and circadian rhythms in healthy and psychiatric participants: A systematic review and meta-analysis of randomized controlled trials. Neuropsychopharmacology47(8): 1523–1536.
32.
PalanSSchitterC (2018) Prolific.ac—A subject pool for online experiments. Journal of Behavioral and Experimental Finance17: 22–27.
33.
ParkerGBBrotchieHGrahamRK (2017) Vitamin D and depression. Journal of Affective Disorders208: 56–61.
34.
PergamsORWZaradicPA (2008) Evidence for a fundamental and pervasive shift away from nature-based recreation. Proceedings of the National Academy of Sciences105(7): 2295–2300.
35.
PludowskiPHolickMFPilzS, et al. (2013) Vitamin D effects on musculoskeletal health, immunity, autoimmunity, cardiovascular disease, cancer, fertility, pregnancy, dementia and mortality—A review of recent evidence. Autoimmunity Reviews12(10): 976–989.
36.
PotterGDMSkeneDJArendtJ, et al. (2016) Circadian rhythm and sleep disruption: Causes, metabolic consequences, and countermeasures. Endocrine Reviews37(6): 584–608.
37.
R Core Team (2022) R: A language and environment for statistical computing. R Foundation for Statistical Computing. https://www.R-project.org/
38.
RishiMAAhmedOBarrantesPJH, et al. (2020) Daylight saving time: An American Academy of Sleep Medicine position statement. Journal of Clinical Sleep Medicine16(10): 1781–1784.
39.
RoennebergTWinnebeckECKlermanEB (2019) Daylight saving time and artificial time zones – A battle between biological and social times. Frontiers in Physiology10: 944.
40.
RoennebergTWirz-JusticeAMerrowM (2003) Life between clocks: Daily temporal patterns of human chronotypes. Journal of Biological Rhythms18(1): 80–90.
41.
RutterfordCCopasAEldridgeS (2015) Methods for sample size determination in cluster randomized trials. International Journal of Epidemiology44(3): 1051–1067.
42.
Sancho-DomingoCCarballoJLColoma-CarmonaA, et al. (2021) Brief version of the Pittsburgh Sleep Quality Index (B-PSQI) and measurement invariance across gender and age in a population-based sample. Psychological Assessment33(2): 111–121.
43.
ScottAJWebbTLMartyn-St JamesM, et al. (2021) Improving sleep quality leads to better mental health: A meta-analysis of randomised controlled trials. Sleep Medicine Reviews60: 101556.
44.
ShimuraASugiuraKInoueM, et al. (2020) Which sleep hygiene factors are important? Comprehensive assessment of lifestyle habits and job environment on sleep among office workers. Sleep Health6(3): 288–298.
45.
ShinTDavisonMLLongJD (2017) Maximum likelihood versus multiple imputation for missing data in small longitudinal samples with nonnormality. Psychological Methods22(3): 426–449.
46.
SmolenskyMHSackett-LundeenLLPortaluppiF (2015) Nocturnal light pollution and underexposure to daytime sunlight: Complementary mechanisms of circadian disruption and related diseases. Chronobiology International32(8): 1029–1048.
47.
St-OngeM-PGrandnerMABrownD, et al. (2016) Sleep duration and quality: Impact on lifestyle behaviors and cardiometabolic health: A scientific statement from the American Heart Association. Circulation134(18): e367–e386.
48.
TähkämöLPartonenTPesonenA-K (2019) Systematic review of light exposure impact on human circadian rhythm. Chronobiology International36(2): 151–170.
49.
WackerMHolickMF (2013) Sunlight and vitamin D. Dermato-Endocrinology5(1): 51–108.
50.
YaremychHEPreacherKJHedekerD (2023) Centering categorical predictors in multilevel models: Best practices and interpretation. Psychological Methods28(3): 613–630.
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