My last post was on the topic of sleep regularity, night-to-night consistency in bedtimes and wake times. Shortly after I posted it, I became aware of a new study that also shows the consequences of irregular sleep. While most studies of adolescent sleep and emotion regulation rely only on self-report measures, Amanda Baker and colleagues at UCLA used fMRI scans to discover how key physiological mechanisms are affected by irregular sleep. Adolescents wore actigraphs for two weeks while they slept and reported each night before bedtime on stressors they were currently experiencing due either to demands placed on them or interpersonal conflict. Each morning, they rated how rested they felt after sleeping. After two weeks, fMRI scans were performed.
A large body of research on adults and adolescents has shown that shorter sleep often leads to emotional dysregulation. The limbic areas of the brain are particularly activated during arousal and stress, and during sleep, there is bidirectional connectivity between these areas and the cortex. While ethical constraints preclude conducting sleep deprivation studies with children and adolescents, in numerous studies with adults whose sleep has been intentionally shortened, this connectivity is diminished and the cortical regions are less enabled to tamp down the limbic arousal.
It is assumed that the same effects would be seen in adolescents. Even though experimental deprivation studies cannot be done, there is an aspect of sleep patterns that can be studied naturally. Adolescents most often do not sleep long enough during the school week, and then sleep longer on the weekends. There are also many instances when they might stay up later on some school nights than others, constituting another source of irregularity in hours slept. Night-to-night consistency has been studied much less than sleep duration, but evidence from studies with adults shows some negative effects. The authors of this study wanted to determine the effects of sleep irregularity in adolescents on connectivity between two areas of the brain.
The results: Adolescents with greater night-to-night variability reported more stressors to the extent that only one additional stressful demand led to 10 minutes shorter sleep and more variability. The scans indicated that like the sleep deprivation studies with adults, adolescents who had more variability in sleep timing had limbic areas that remained more activated and showed less connectivity with the cortical regions than their peers whose sleep was less variable.
These results add to the growing realization among researchers that variability is of equal importance as duration in ensuring sufficient restorative sleep. Public health policy recommendations have focused largely on establishing how long children and adolescents should be sleeping for optimal performance and well-being. Those recommendations need to be extended to telling parents and adolescents that going to sleep and waking up at around the same time every day, including weekends, is also necessary for realizing the benefits of “better” sleep.
Source : Psychology Today