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What is a circadian rhythm?
The human body has a "circadian rhythm" that it developed to adapt to environmental changes caused by the Earth's rotation. You could also call it a daily cycle regulated by our internal body clock.
Circadian rhythms are closely involved in sleep-wake cycles, blood pressure, body temperature, and hormone secretion. For example, when you travel abroad, you might feel unwell, and this is because the time difference disrupts your body's rhythm.
Can a disrupted circadian rhythm lead to sleep disorders?
The average human circadian rhythm (daily fluctuation) is said to be about 24.2 hours. Therefore, if left unadjusted, our daily schedule would shift later and later. However, humans adjust their internal clocks daily to maintain social lives.
When this adjustment mechanism fails, the body clock cannot synchronize with a 24-hour cycle, leading to difficulties attending school or work on time and problems maintaining a social life. This disruption in rhythm is called "circadian rhythm sleep disorder" and manifests with the following symptoms:
Types of Circadian Rhythm Sleep Disorders
Delayed Sleep Phase Syndrome
In delayed sleep phase syndrome, the sleep-wake rhythm is delayed, making it impossible to fall asleep until early morning, and waking up also occurs later. While sleep duration and patterns are often normal, falling asleep between 3-6 AM means waking up around 11 AM to 2 PM. This is common during adolescence and young adulthood, leading to increased tardiness and absences from school.
Advanced Sleep Phase Syndrome
Conversely, advanced sleep phase syndrome occurs when the rhythm shifts earlier, causing the bedtime to move earlier. This results in feeling sleepy in the evening and waking up in the middle of the night. Although considered less severe than delayed sleep phase syndrome, it can lead to decreased concentration due to drowsiness during working hours or insufficient sleep due to late bedtimes and early morning awakenings.
While the two disorders above are characterized by consistent, albeit unusual, sleep times, there is also "non-24-hour sleep-wake rhythm disorder (free-run)," where the sleep-wake rhythm shifts progressively each day. It is often said to shift by about an hour per day. This is particularly common in visually impaired individuals because their internal clocks cannot be regulated to a 24-hour cycle by light, though it rarely occurs in sighted individuals as well.
Other circadian rhythm sleep disorders include irregular sleep-wake patterns, which lack a clear sleep-wake circadian rhythm and are seen in patients with brain dysfunction; shift work sleep disorder, which is the discomfort experienced by shift workers; and jet lag (jet lag syndrome).
Habits for regulating your circadian rhythm
What is effective for adjusting the circadian rhythm?
The biggest factor is "light." Exposure to strong light in the morning is said to advance the body clock. Therefore, people with delayed sleep phase syndrome are advised to expose themselves to strong light from morning to noon, while those with advanced sleep phase syndrome are advised to do so in the evening or later.
"Eating" is also said to be an important factor in regulating the body clock's rhythm. Breakfast, in particular, is essential and is considered to act as an alarm clock for the body.
Another important factor is "exercise." Moderately moving your body and increasing your activity level during the day is crucial for improving sleep quality and regulating your rhythm. If you are not active enough during the day, your body will have difficulty entering sleep mode.
Master your body clock by following these 7 habits!
Based on the above, here are 7 habits to regulate your body clock:
- Maintain a consistent wake-up time: It's important to be consistent on both weekdays and weekends. Waking up late on weekends can prevent your rhythm from returning on Monday, leading to a mild jet lag-like state.
- When you wake up in the morning, expose yourself to the morning sun.
- Eat a proper breakfast.
- Be active during the day.
- Be aware of body temperature changes: The timing when body temperature drops is when it's easiest to fall asleep. By adjusting your bath or shower routine, you can better control your sleep.
- Avoid strong light as much as possible at night: Don't look at your smartphone before bed.
- Strive for a regular lifestyle.
