Social Jetlag: Why Sleeping In on Weekends is More Dangerous Than You Think

A man gazing at the rainy city skyline after he gets up.

At the end of the week, are you one to silence your Saturday morning alarm? Prepare for a weekend of rest after five days of school, work, or study? Even if you’re finally hitting that eight-hour goal, did you know that this habit has a hidden health cost?

Circadian Rhythm

Established by your daily behavior within the 24-hour day-night cycle, your body internalizes a biological “clock” to coordinate its physical processes (Vitaterna et al., 2001). Studies find that this clock, known as your circadian rhythm, organizes your bodily functions (e.g., cell repair, inflammation, metabolism) into a rhythmic pattern (Fagiani et al., 2022). In this process, your circadian rhythm synchronizes internal changes with the external environment through routine predictivity (Vitaterna et al., 2001). Such a relation is key to survival and well-being, but hitting that snooze button on the weekend alters the rhythm.

Social Jet Lag

After five weekdays built around work or school, you’ve established nighttime habits that are biologically ingrained as the schedule that your body expects to remain the same over the weekend. As your body isn’t naturally prepared for the separation of workdays from a non-work weekend, time spent sleeping in or staying awake later on the weekend affects physiological pathways inside cells in the body. As a result of these changes, your body undergoes the phenomenon of social jet lag (SJL), described as the “discrepancy between social and biological time” (Whittmann et al., 2006). SJL’s magnitude of effect varies, intensifying as the difference between sleep onset on free days and sleep onset on workdays increases (Jankowski, 2017). Higher SJL values promote the tendency for health-detrimental actions like smoking (Wittmann et al., 2006) and physical inactivity (Rutters et al., 2014). Beyond this action, the disruption posed by SJL is compounded by the underlying mechanisms of the altered circadian rhythm.

A clock on a lush field, capturing the transitional beauty of day and evening as sunlight gently fades over the horizon.

Consequences of Disrupted Rhythm

Significant departure from your “natural” circadian rhythm unleashes a laundry list of potential struggles and disorders. In particular, circadian sleep-wake disorders (CRSWDs) arise from circadian rhythm disruption (CRD); this term encompasses the numerous sleep conditions that irregular rhythm precedes (Ingram, 2020). For instance, 25.8% of adolescents and young adults with CRSWDs developed impaired glucose tolerance (Toyoura et al., 2020), a precursor to type two diabetes. In older adults, CRD increases the risk of cardiovascular disease by 20.5% (Sohail et al., 2015). CRSWDs contain a wide array of conditions detrimental to all ages, including psychiatric ailments, metabolic disorders, and cardiovascular disease (Ingram, 2020). However, the greatest concern revolves around CRSWDs’ suppression of the immune system. 

As CRD derails your body’s secretion of cytokines (signal proteins that cells use to communicate with one another), your immune cells fail to receive proper instructions and their production becomes imbalanced, inhibiting immune system function as weaknesses to select diseases occur (Zeng et al., 2024). Moreover, CRD impairs DNA repair (Zeng et al., 2024), leading to mutations that can cause cancer. Studies reveal that night shift workers, individuals working overnight hours such as 11:00 PM to 7:00 AM, are especially vulnerable. Norwegian nurses who worked night shifts for over 30 years were 36% more likely to develop breast cancer (Schernhammer et al., 2001), and Spanish males with at least one year of working night shifts were 14% more likely to develop prostate cancer (Papantoniou et al., 2015). In general, breast and prostate cancer emerge as the most common cancers propagated from CRD, surprisingly, modeled in later meal times alongside night shifts (Masri & Sassone-Corsi, 2018).

In addition to the decline of these direct biological processes and raised cancer odds, CRD infringes upon your ability to socialize in daily life. Although typical CRSWD victims separate socializing from their routine sleep schedule, some force synchronization between social time and habitual sleep by staying awake and social beyond the hours the body expects, rejecting sleepiness in favor of prolonged conversation (Akashi et al., 2020). Repeated engagement with this behavior fosters what Akashi et al. (2020) deems as latent CRSWD, or LCRSWD, which evades standard CRSWD detection while initiating the same harmful effects. Considering the surreptitious nature of this condition, prevalence may greatly exceed Kerkhof’s (2017) finding that approximately 5.3% of the Dutch population from ages 18-70 possessed CRSWD.

Conclusion

You may have believed that those extra hours of weekend sleep act as a natural offset to recover from sleepless workdays, clearing away your sleep-deprived state with a seemingly healthy snooze. However, biological systems don’t obey this logic. No matter how refreshing the rest, by pressing snooze on that weekend alarm you scramble your internal timers, ensuring that the transition from weekend to workday delivers a shock to your body. What first seems like free time isn’t as free as it seems, and that altering of the circadian rhythm bears some serious consequences.

Between the undesirable behaviors inspired by social jet lag and the harms of circadian rhythm disruption, the quantity of sleep falls short of serving as a universal health solution. By maintaining a consistent time of going to sleep schedule across the week, we can stop fighting biology and help our body towards better health. So, the next time you’re tempted to ignore that alarm on a Saturday morning, remember that those extra hours are more likely to be a long-term punishment rather than a gift.

Written by Benjamin Haselhuhn and edited by Aldrin V. Gomes, PhD

References

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