Sleep during "lockdown" highlighted the need to rethink the concept of weekend catch-up sleep.

PURPOSE Many people believe in their ability to sleep for longer time on weekends to make up for sleep lost due to early wakeups on weekdays. This widely held belief was not supported by the simulations of rise- and bedtimes on weekdays and weekends with a sleep-wake regulating model. The simulations suggested the inability to extend sleep on any of two weekend nights and they predicted identical weekend sleep durations for weeks with relatively earlier and relatively later weekday risetimes. By April 2020, about half of the world's population was under some form of "lockdown" due to the COVID-19 pandemic. This "lockdown" provided a new opportunity to demonstrate the predictive power of the sleep-wake regulating models. Therefore, the purpose of this report was to support the prediction of identity of weekend sleep durations after weeks with earlier and later weekday wakeups. METHODS Weekend and weekday rise- and bedtimes before and during "lockdown" for 31 samples were taken from recent journal publications. Time in bed on weekends and 12 other measures of sleep duration and timing were calculated and simulated. RESULTS For only one of 13 measures, weekend time in bed, statistical analysis did not yield a statistically significant difference between the estimates obtained before and during "lockdown". The model-based simulations pointed to the 0.3-h delay of the sleep-wake cycle in response to the 1-h delay of weekday risetime during "lockdown". CONCLUSION The model-based prediction was confirmed, thus, highlighting again the necessity to rethink the concept of weekend catch-up sleep.