Browsing by Author "Kitamura, Shingo"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- Outdoor daylight exposure and longer sleep promote wellbeing under COVID‐19 mandated restrictionsPublication . Korman, Maria; Tkachev, Vadim; Reis, Cátia; Komada, Yoko; Kitamura, Shingo; Gubin, Denis; Kumar, Vinod; Roenneberg, TillLight is an important regulator of daily human physiology in providing time-of-day information for the circadian clock to stay synchronised with the 24-hr day. The coronavirus disease 2019 (COVID-19) pandemic led to social restrictions in many countries to prevent virus spreading, restrictions that dramatically altered daily routines and limited outdoor daylight exposure. We previously reported that sleep duration increased, social jetlag decreased, and mid-sleep times delayed during social restrictions (Global Chrono Corona Survey, N = 7,517). In the present study, we investigated in the same dataset changes in wellbeing and their link to outdoor daylight exposure, and sleep–wake behaviour. In social restrictions, median values of sleep quality, quality of life, physical activity and productivity deteriorated, while screen time increased, and outdoor daylight exposure was reduced by ~58%. Yet, many survey participants also reported no changes or even improvements. Larger reductions in outdoor daylight exposure were linked to deteriorations in wellbeing and delayed mid-sleep times. Notably, sleep duration was not associated with outdoor daylight exposure loss. Longer sleep and decreased alarm-clock use dose-dependently correlated with changes in sleep quality and quality of life. Regression analysis for each wellbeing aspect showed that a model with six predictors including both levels and their deltas of outdoor daylight exposure, sleep duration and mid-sleep timing explained 5%–10% of the variance in changes of wellbeing scores (except for productivity). As exposure to daylight may extenuate the negative effects of social restriction and prevent sleep disruption, public strategies during pandemics should actively foster spending more daytime outdoors.
- Relaxation of social time pressure reveals tight coupling between daily sleep and eating behavior and extends the interval between last and first mealPublication . Korman, Maria; Fleischmann, Chen; Tkachev, Vadim; Reis, Cátia; Komada, Yoko; Gubin, Denis; Kumar, Vinod; Kitamura, Shingo; Roenneberg, TillStudy Objectives: As a day-active species, humans abstain from some or all foods and beverages and rest at night. The modern social clock diverged from the natural light–dark clock with far-stretching consequences for both fasting/eating and sleep/wake daily cycles. Methods: During the COVID-19 pandemic, prolonged social restrictions (SRs) offered a quasi-experimental protocol to directly test the impact of the relaxed social clock on eating and sleep behaviors and the coupling between them. Results: Using data from a global survey of 5747 adults (mean age 37.2 ± 13.7, 67.1% females, 100% worked/studied), we show that relaxation of the social time pressure (STP) during SRs led, on average, to a 42 min increase in the habitual fasting duration (FD, interval between the last and the first meal) (from 12:16 ± 2:09 to 12:57 ± 2:04) and a 34 min delay in the fasting window. FD was extended by lengthening both the presleep fasting and sleep durations. Pre-SR breakfast eaters delayed sleep and fasting, while breakfast skippers delayed sleep and advanced meals. Stopping alarm use on workdays was associated with a larger increase in FD. The correlations between chronotype, FD, and the mid-fasting time became more robust during SR. Conclusions: We conclude that relaxed STP extends habitual FD and promotes co-alignment of daily fasting and sleeping. Given the finding that the sleep-fasting phase relationship during SRs remained stable, we suggest that a “daily sleep-fasting structure” may be a novel circadian marker quantifying the coupling between daily rhythms. These results may inform strategies of public circadian health management.