Ah, the weekend. The time for sleeping in. That’s a good thing, right? Yes! But wait, there’s more.

For adults, adding some extra sleep to your weekend mornings might be the only way you can catch up a bit (that is, if the small people in your home will let you!). If you’re adding no more than an hour beyond your normal wake up time, you’re probably fine.

The problem comes when we combine those later mornings with later bedtimes as well on the weekend. Why? Because our body doesn’t keep a perfect 24-hour rhythm. Every morning there’s a “reset” on our internal clocks, based on the presence of light in the morning. [1]Duffy, J. F., & Czeisler, C. A. (2009). Effect of Light on Human Circadian Physiology. Sleep Medicine Clinics, 4(2), 165–177. http://doi.org/10.1016/j.jsmc.2009.01.004 This is a good thing–it’s what allows us to change time zones, or to shift in and out of Daylight Savings Time: our internal time is able to adapt to the social time.

Did you know that for many people who are completely blind, their sleep cycle will constantly shift around the clock because of the absence of light? [2]Sack, R. L., Lewy, A. J., Blood, M. L., Keith, L. D., & Nakagawa, H. (1992). Circadian rhythm abnormalities in totally blind people: incidence and clinical significance. The Journal of Clinical Endocrinology & Metabolism, 75(1), 127–134. http://doi.org/10.1210/jcem.75.1.1619000

But just like you probably feel a little out of whack when adjusting to a different time, we cause our bodies to feel out of whack when we stay up late and sleep in late on the weekend. Monday morning hits, and you discover “social jet lag.” [3]Wittmann, M., Dinich, J., Merrow, M., & Roenneberg, T. (2006). Social Jetlag: Misalignment of Biological and Social Time. Chronobiology International, 23(1–2), 497–509. http://doi.org/10.1080/07420520500545979

Your body has shifted to a later time and is protesting the rude awakening you’re giving it.

This happens often in adolescents who would prefer to stay up late and sleep in late, but have to contend with early school start times–or just parents who are perplexed that their teen is still asleep at noon.

In can also happen with very little ones, if bedtime is happening too late and morning routines (daycare, siblings waking up) are waking your child before they would prefer to be up. If you notice your child sleeping in when he or she has the chance, it’s likely that he or she isn’t getting enough sleep the rest of the time. Additionally, although adults might be able to adjust to an hour of variation in our sleep schedules, babies and young children have far less wiggle room and might be even more sensitive to changes.[4]Doi, Y., Ishihara, K., & Uchiyama, M. (2015). Associations of chronotype with social jetlag and behavioral problems in preschool children. Chronobiology International, 32(8), 1101–1108. http://doi.org/10.3109/07420528.2015.1063503

When we sleep out of sync with our internal clock, there’s a greater risk of weight gain and mood swings.[5]American Academy of Sleep Medicine. (2017, June 5). Social jet lag is associated with worse mood, poorer health and heart disease: Delaying your sleep schedule on weekends has health consequences. ScienceDaily. Retrieved July 21, 2017 from www.sciencedaily.com/releases/2017/06/170605085326.htm One study of elementary aged children found that a difference of an hour or more in bedtime and wake time across the week significantly increased the child’s risk of behavioral problems.[6]Biggs, S. N., Lushington, K., van den Heuvel, C. J., Martin, A. J., & Kennedy, J. D. (2011). Inconsistent sleep schedules and daytime behavioral difficulties in school-aged children. Sleep Medicine, 12(8), 780–786. http://doi.org/10.1016/j.sleep.2011.03.017 Preschoolers are more likely to be hyperactive or experience other behavioral problems.[7]Doi, Y., Ishihara, K., & Uchiyama, M. (2015). Associations of chronotype with social jetlag and behavioral problems in preschool children. Chronobiology International, 32(8), 1101–1108. http://doi.org/10.3109/07420528.2015.1063503 Bottom line: this isn’t a good thing.

What can you do? As best you can, keep a consistent bedtime and wake time. If you or your little one need the extra zzz’s in the morning, go ahead and catch up–and see if you can challenge yourself to regularly make bedtime just a little bit earlier.

References   [ + ]