Simulation of the Ontogeny of Social Jet Lag: A Shift in Just One of the Parameters of a Model of Sleep-Wake Regulating Process Accounts for the Delay of Sleep Phase Across Adolescence

Abstract

The term “social jet lag” was introduced for defining the conflict between social and biological clocks due to the general practice of shifting weekday risetime on early morning hours. The phase delay of the sleep-wake cycle during adolescence is one of the most remarkable features of the ontogenesis of sleep that is incompatible with early school start times. It was previously proposed that the process of accumulation of sleep pressure during wakefulness is slowing down in post-pubertal teens to allow them to stay awake for a longer period of time thus causing the delay of their bedtime. In order to examine this proposition, we traced the ontogeny of social jet lag using sleep times reported for 160 samples of study participants of different ages as an input to a model of sleep-wake regulatory process. The simulations suggested that a gradual change in just one of the model’s parameters, the time constant of wakefulness phase of the sleep-wake regulatory process, might explain the association of the transition between childhood and adulthood with the prolongation of time staying awake, delay of sleep time, and reduction of sleep duration. We concluded that the implication of the sleep-wake regulating model would be of help for understanding precisely how social jet lag varies with age and what are the chronophysiological causes of this variation.

Sleep during “lockdown” highlighted the need to rethink the concept of weekend catch-up sleep

“…Such a prediction fully disagrees with the widely held belief in human ability to make up missed weekday sleep by increasing sleep duration on weekend nights. Previous simulations [2,4,5] and the present model-based simulations (Fig. 1) did not support the concept of catching up on missed weekday sleep during the following weekend.…”

“…The following response of sleep to "lockdown" can be expected from the results of previous simulations of sleep times [2,4,5]. Due to a failure to accumulate "sleep debt" during weekdays, a shift from an earlier risetimes before "lockdown" to a later weekday risetimes during "lockdown" must lead to an increase of weekday sleep duration during "lockdown".…”

“…The intuitive view of the wake-sleep alternations on weekdays and weekends might be associated with the alternation of a reduced weekday sleep and a lengthened weekend sleep with such a process of accumulation of "sleep debt" and its "payment", respectively. However, the results of simulation of weekday and weekend bed-and risetimes [2] with a sleep-wake regulating model [3] has indicated that, irrespective of whether sleep was terminated spontaneously (on a weekend night) or somewhat earlier (on a weekday night), each of the everyday switches of the level of sleep pressure from its buildup to its decay occurred exactly at the model-predicted upper threshold, not above this threshold (Fig. 1A and C).…”

“…1A and C). This implies that [2,4,5]. By April 2020, due to the COVID-19 pandemic about half of the world's population was under some form of "lockdown" [6].…”

Quo Vadis, Chronopsychology?

“…As an enormous number of publications contain data on the time of day at which study participants go to bed and get up on week and weekend days, data on hundreds of cohorts were simulated using the rhythmostat model described above. The simulation did not show any signs of either normal or social jet lag in the majority of cohorts [Putilov and Verevkin, 2018;Putilov et al, 2020b]. It turned out that what was termed social jet lag is actually no more than loss of sleep on weekdays which can be calculated using the model for each of these cohorts and in the longer term for each individual person [Putilov et al, 2020a;Putilov et al, 2020b].…”