Browsing by Author "Roenneberg, Till"
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- 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.
- Patients with delayed sleep-wake phase disorder sleep less during daylight saving timePublication . Reis, Cátia; Pilz, Luísa K.; Kramer, Achim; Lopes, Luísa Vaqueiro; Paiva, Teresa; Roenneberg, Till
- Social jetlag, a novel predictor for high cardiovascular risk in blue-collar workers following permanent atypical work schedulesPublication . Madeira, Sara Gamboa; Reis, Cátia; Paiva, Teresa; Moreira, Carlos Santos; Nogueira, Paulo; Roenneberg, TillCardiovascular diseases cause >4 million deaths each year in Europe alone. Preventive approaches that do not only consider individual risk factors but their interaction, such as the Systematic COronary Risk Evaluation (SCORE), are recommended by European guidelines. Increased cardiovascular risk is associated with shift-work, surely interacting with the concurrent conditions: disruption of sleep, unhealthy behaviours, and circadian misalignment. Social jetlag (SJL) has been proposed as a way to quantify circadian misalignment. We therefore investigated the association between SJL and cardiovascular health in a cross-sectional observational study involving blue-collar workers, who either worked permanent morning, evening, or night shifts. Sociodemographic, health and productivity data were collected through questionnaires. Blood pressure and cholesterol were measured and the cardiovascular risk was estimated according to the relative risk SCORE chart. Bivariate analysis was performed according to the cardiovascular risk and the relationship between SJL and high cardiovascular risk was analysed through logistic regression. Cumulative models were performed, adjusted for various confounding factors. After 49 exclusions, the final sample comprised 301 workers (56% males; aged <40 years, 73%). Mean standard deviation (SD) SJL was 1:57 (1:38) hr (59.4% ≤2 hr). Cardiovascular risk was high in 20% of the sample. Multivariate analysis revealed SJL to be an independent risk factor for high cardiovascular risk. Each additional hour of SJL increased this risk by >30% (odds ratio 1.31, 95% confidence interval 1.02-1.68). This is the first study indicating that SJL potentially increases cardiovascular risk, and suggests that sleep and individual circadian qualities are critical in preventing negative health impacts of shift-work.
- The impact of daylight‐saving time (DST) on patients with delayed sleep‐wake phase disorder (DSWPD)Publication . Reis, Cátia; Pilz, Luísa K.; Kramer, Achim; Lopes, Luísa V.; Paiva, Teresa; Roenneberg, TillDue to time zones, sun time and local time rarely match. The difference between local and sun time, which we designate by Solar Jet Lag (SoJL), depends on location within a time zone and can range from zero to several hours. Daylight Saving Time (DST) simply adds one hour to SoJL, independent of location. We hypothesized that the impact of DST, is particularly problematic in patients with Delayed Sleep-Wake Phase Disorder (DSWPD), worsening their sleep debt. DSWPD is characterized by a chronic misalignment between the internal and social timing, reflected by an inability to fall asleep and wakeup at conventional or socially acceptable times. We analysed the clinical records of 162 DSWPD patients from a sleep medicine centre in Lisbon, Portugal (GMTzone), and separated them into two groups: the ones diagnosed across DST or Standard Time (ST). We included 82 patients (54.9% male; age: median [Q1, Q3] 34.5 [25.0, 45.3]; range 16-92; 54 in DST and 28 in ST) who had Dim Light Melatonin Onset (DLMO) measured as a marker for the circadian phase and sleep timing (onset, SO, mid-point, MS and end, SE) self-reported separately for work- and work-free days. Differences between ST and DST were compared using Mann-Whitney or Student's t tests. On a weekly average, patients in DST slept an hour less (62 min. p