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Objective In a convenience sample of athletes, we conducted a survey of COVID-19-mediated lockdown (termed ‘lockdown’ from this point forward) effects on: (i) circadian rhythms; (ii) sleep; (iii) eating; and (iv) training behaviors. Methods In total, 3911 athletes [mean age: 25.1 (range 18–61) years, 1764 female (45%), 2427 team-sport (63%) and 1442 elite (37%) athletes] from 49 countries completed a multilingual cross-sectional survey including the Pittsburgh Sleep Quality Index and Insomnia Severity Index questionnaires, alongside bespoke questions about napping, training, and nutrition behaviors. Results Pittsburgh Sleep Quality Index (4.3 ± 2.4 to 5.8 ± 3.1) and Insomnia Severity Index (4.8 ± 4.7 to 7.2 ± 6.4) scores increased from pre- to during lockdown (p

Additional file 1: Supplementary Table 1. Bivariate correlations.

Inter-individual variability exists in recovery from jetlag following travel across time zones. Part of this variation may be due to genetic differences at the variable number tandem repeat (VNTR) polymorphism of the PERIOD3 (PER3) gene as this polymorphism has been associated with chronotype and sleep, as well as sensitivity to blue light on melatonin suppression. To test this hypothesis we conducted a laboratory-based study to compare re-entrainment in males genotyped as PER34/4 (n = 8) and PER35/5 (n = 8) following simulated eastward travel across six time zones. The recovery strategy included morning blue-enriched light exposure and appropriately-timed meals during the first 24 h after simulated travel. Dim light melatonin onset (DLMO), sleep characteristics, perceived sleepiness levels (Stanford Sleepiness Scale), and resting metabolic parameters were measured during constant routine periods before and after simulated travel. While DLMO time was similar between the two groups prior to simulated eastward travel (p = .223), it was earlier in the PER35/5 group (17h23 (17h15; 17h37)) than the PER34/4 group (18h05 (17h53; 18h12)) afterwards (p = .046). During resynchronisation, perceived sleepiness and metabolic parameters were similar to pre-travel in both groups but sleep was more disturbed in the PER35/5 group (total sleep time: p = .008, sleep efficiency: p = .008, wake after sleep onset: p = .023). The PER3 VNTR genotype may influence the efficacy of re-entrainment following trans-meridian travel when blue-enriched light exposure is incorporated into the recovery strategy on the first day following travel.

Additional file 4: Table A1. Ordered logistic regression models associating BMI z-score quartile (dependent variable) with average bedtime (Model 3), wake-up time (Model 4) and nap duration (Model 5).

Supplemental Material, sj-docx-3-ahp-10.1177_0890117121992288 for Associations Between Self-Reported Sleep Duration and Mortality in Employed Individuals: Systematic Review and Meta-Analysis by Paula R. Pienaar, Tracy L. Kolbe-Alexander, Willem van Mechelen, Cécile R. L. Boot, Laura C. Roden, Estelle V. Lambert and Dale E. Rae in American Journal of Health Promotion

Supplemental Material, sj-docx-2-ahp-10.1177_0890117121992288 for Associations Between Self-Reported Sleep Duration and Mortality in Employed Individuals: Systematic Review and Meta-Analysis by Paula R. Pienaar, Tracy L. Kolbe-Alexander, Willem van Mechelen, Cécile R. L. Boot, Laura C. Roden, Estelle V. Lambert and Dale E. Rae in American Journal of Health Promotion

Supplemental Material, sj-docx-1-ahp-10.1177_0890117121992288 for Associations Between Self-Reported Sleep Duration and Mortality in Employed Individuals: Systematic Review and Meta-Analysis by Paula R. Pienaar, Tracy L. Kolbe-Alexander, Willem van Mechelen, Cécile R. L. Boot, Laura C. Roden, Estelle V. Lambert and Dale E. Rae in American Journal of Health Promotion