It’s the week after the “spring forward” time change for daylight saving time (DST). How are you feeling? Many people feel slight groggy the first Monday after DST starts, due to losing an hour of sleep, but the adverse effects can linger for days or even weeks! Circadian rhythms can affect sleep. Are you looking for proof? One sobering statistic shares that fatal car accidents increase by 6% the week after DST begins.
The term circadian means ‘about a day.’ The circadian clock, located deep in the brain in the suprachiasmatic nucleus (SCN), coordinates systems throughout the body, including sleep and hormones. Exposure to light keeps our circadian rhythm tightly linked to the local 24-hour environment.
Circadian Influence on S
In normal sleep, two processes interact to keep people awake for approximately 16 hours and asleep for around eight hours. One process keeps track of the need to sleep, while the other method (controlled by the circadian clock), provides strong signals favoring sleep or waking at specific times.
Sleep disorders can be caused by a mismatch between sleep needs and the timing of the signals from the circadian clock. The result can be fatigue, poor work performance, and sleep disturbances, particularly difficulty falling asleep or waking up at desired times.
Night shift work
People who work at night often experience reduced alertness and job performance during their shift, as well as inadequate daytime sleep ( one to three hours less) when they return home. They may also have trouble staying awake while driving home.
Advanced Sleep Phase Syndrome (ASPS)
ASPS folks are “early birds” with bedtimes around 6:00- 9:00 pm, and early morning awakening around 1:00- 3:00 am. Sleep quality is generally normal if they can go to bed early, but poor if trying to stay up late.
Delayed Sleep Phase Syndrome (DSPS)
DSPS people are extreme “night owls,” with bedtimes around 3:00-6:00 am and wake times around 12:00-3:00 pm. Sleep quality and duration are normal when they are allowed to sleep at their preferred biological times, but DSPS symptoms appear when trying to sleep earlier because of work or school demands.
Conflicts between the circadian clock and work/social demands can lead to poor sleep. Careful control of exposure to light and sleep timing can help people adjust their clocks to the requirements of their jobs and social lives.
Boivin, D.B. & Boudreau, P. (2013). Circadian rhythms and insomnia: Approaching the time barrier. Insomnia Rounds, 2(4), 1-8. https://css-scs.ca/files/resources/insomnia-rounds/150-010_Eng.pdf
Fritz, J., Vopham, T., Wright, K., Vetter, C., & Fritz, J. (2020). A chronobiological evaluation of the acute effects of Daylight Saving Time on traffic accident risk. Current Biology, 30(4), 729–735.e2. https://doi.org/10.1016/j.cub.2019.12.045
Walker, M. (2018). Why We Sleep: Unlocking the Power of Sleep and Dreams. Scribner.
Elaine Waddington Lamont, Ph.D., M.S.W., R.S.W. is a clinician at CFIR (Ottawa) with experience in helping people to rediscover and harness their inner resources. Elaine has spent the past 15 years doing neuroscience research aimed at better understanding how the environment influences biological rhythms like sleep, hormones, and metabolism, which, in turn, affects our mental health.