Seasonal changes in sleep duration and sleep problems: A prospective study in Japanese community residents

Abstract

Background A scientific understanding of the effects of seasonal changes on sleep duration and sleep problems such as insomnia and hypersomnia has yet to be elucidated; however, such an understanding could aid the establishment of an optimal sleep hygiene program to treat such problems. Methods We investigated the effects of seasonal changes on sleep duration and sleep problems in Japanese community residents. Data on 1,388 individuals aged 15–89 years who participated in the Survey of Seasonal Variations in Food Intakes conducted by the National Institute of Health and Nutrition of Japan (2004–2007) were analyzed. Participants completed a questionnaire including items on sleep duration and sleep problems (difficulty initiating sleep [DIS], difficulty maintaining sleep [DMS]/early morning awakening [EMA], and excessive daytime sleepiness [EDS]). Data were prospectively collected at four time points (spring, summer, fall, and winter). Results Seasonal changes in sleep duration were found, with the longest in winter and the shortest in summer (winter–summer difference: 0.19 h). The seasonality of sleep duration was influenced by age, sex, and residential area. In terms of age, seasonal changes in sleep duration were found in the middle and old age groups, but not in the young age group. Seasonal changes in the frequencies of sleep problems were found for some items in the young age group (DMS/EMA and EDS) and middle age group (DIS and DMS/EMA); however, no such changes were observed in the old age group. Conclusion Seasonal effects on sleep and sleep problems were found in Japanese community residents, but these varied between age groups. Furthermore, seasonal changes in sleep duration were influenced by sex and residential area.

Sleep in the land of the midnight sun and polar night: The Tromsø study

“…The heterogeneity of study designs make comparisons across studies difficult. For example, several studies have been conducted in Japan (Itani et al 2016;Hashizaki et al 2018;Suzuki et al 2019), a country with relatively little variation in hours of daylight throughout the year (<5 h difference between December and June). As also suggested by Suzuki et al (Suzuki et al 2019), it is more likely that the observed differences in those studies may be more related to seasonal differences in temperature, rather than by differences in daylight.…”

“…For example, several studies have been conducted in Japan (Itani et al 2016;Hashizaki et al 2018;Suzuki et al 2019), a country with relatively little variation in hours of daylight throughout the year (<5 h difference between December and June). As also suggested by Suzuki et al (Suzuki et al 2019), it is more likely that the observed differences in those studies may be more related to seasonal differences in temperature, rather than by differences in daylight. In contrast to some earlier studies (Kasper et al 1989;Volkov et al 2007) that have found up to half an hour longer sleep duration in winter compared to summer, we found no evidence of this pattern in the current study, with a difference of only 4 min between the months with the longest and shortest sleep duration.…”

“…Studies conducted in more temperate zones have also explore possible seasonal variation in sleep. For example, a recent Japanese study found longer sleep duration in winter compared to summer; but, the difference was relatively modest (11 min) (Suzuki et al 2019), and another nationwide Japanese study found no significant association between seasonality and insomnia prevalence (Itani et al 2016).…”

<p>Evaluation of the Effects of an Intervention Intended to Optimize the Sleep Environment Among the Elderly: An Exploratory Study</p>

“…[70][71][72] This effect is more pronounced in older people than in other age groups. 73 The present study was probably subject to this seasonality affect. The fact that participants' level of depression did not increase between the start and end of the study therefore reinforces the positive results obtained.…”

Annual rhythms in adults’ lifestyle and health (ARIA): protocol for a 12-month longitudinal study examining temporal patterns in weight, activity, diet, and wellbeing in Australian adults

“…Seasonal differences in energy and nutrient intake have been reported, though they are generally small in magnitude, and the direction of such differences is inconsistent between studies [ 13 , 22 ]. Similarly, some studies have shown that adults sleep more in winter [ 23 , 24 ], while others have shown no seasonal difference in sleep [ 25 , 26 ]. Adult studies in the US and Europe found that people are relatively more active in summer than in winter [ 27 – 29 ].…”