Many people believe that active night life and sleeping during the day is unconditionally bad for health. However, the problem is not simply being active at night. The crucial part is understanding how your internal biological clock is functioning.
The Real Issue: "Circadian Conflict"
Our bodies possess an internal biological clock (Circadian Rhythm) that operates on an approximately 24-hour cycle. This clock does not simply determine bedtime. It plays an important role in regulating the following functions:
- Body temperature
- Hormone secretion
- Focus levels
- Sleepiness
- State of alertness
In other words, we do not simply live by looking at a clock; we live according to our internal biological clock.
Scientific Evidence
Why Feel Tired?
For example, suppose you sleep at 10:00 PM and wake up at 6:00 AM to prepare for work. In terms of sleep duration, you slept for 8 hours, which seems sufficient. However, many people still feel tired in such a routine.
The reason is not simply a lack of sleep duration, but because the time your body wants and the time society demands may differ. Most social systems—such as morning commutes, morning classes, clinic hours, and public office work—are designed around daytime activities.
Social Jetlag
This mismatch between the time the body wants and the time society demands is called Social Jetlag. For example, your body wants to wake up at 9:00 AM, but you must rise at 6:00 AM due to work. Conversely, your body wants to sleep at 2:00 AM, but you must try to sleep at 11:00 PM due to schedules. Repeated gaps can accumulate fatigue.
Scientific Evidence
Social jetlag is a sleep research concept referring to the discrepancy between the biological clock and social timetables. Studies show that the more this jetlag repeats, the higher the likelihood of experiencing fatigue, daytime sleepiness, and lower sleep quality. In particular, people with large differences in sleep patterns between weekdays and weekends are known to be highly susceptible to social jetlag.
Then, Is a Flipped Day/Night Schedule OK?
In conclusion, it does not necessarily lead to health issues. However, a lifestyle where the biological clock is constantly shaken can strain the body. In particular, the biological clock can experience confusion under the following conditions:
- Alternating between day shifts and night shifts
- Bedtime changing drastically every day
- Large differences in sleep duration between weekdays and weekends
Conversely, if you maintain a consistent lifestyle pattern and manage your biological clock stably, you can reduce the negative impacts.
📚 References
- 2017 Nobel Prize in Physiology or Medicine - Discoveries of molecular mechanisms controlling the circadian rhythm, NobelPrize.org.
- National Institute of General Medical Sciences (NIGMS) - Circadian Rhythms Fact Sheet.
- Roenneberg et al. - Social Jetlag Research.
- National Sleep Foundation - Circadian Rhythm and Sleep Timing.
- Caliandro et al. (2021) - Social Jetlag and Related Risks for Human Health.
Disclaimer: The research articles provided here are for informational and educational purposes based on circadian biology and sleep medicine. They do not substitute for professional medical advice, diagnosis, or treatment. If you suspect any chronic sleep disorders, consult a qualified physician.