Circadian Rhythm: A Vital Mechanism for Quality Sleep and Disease Prevention
Many may have heard the term "biological clock," scientifically known as the circadian rhythm. This mechanism, regulated by the nervous system, plays a pivotal role in governing the bodily natural sleep-wake cycle spanning approximately 24.05 hours.
The circadian rhythm has evolved and integrated into the human genome over eons. It regulates various bodily systems, such as hormone production and body temperature, ensuring adequate sleep and aligning with the bodily daily energy demands and wakefulness cycles.
However, more people are experiencing circadian rhythm disorders, or "disrupted body clock” in everyday parlance. This imbalance significantly impacts various aspects of life, most notably sleep quality. In this article, Assist. Prof. Dr. Jirayos Chintanadilok, a physician specialist in sleep medicine, shares valuable insights on the circadian rhythm to help individuals improve their lifestyles and sleep quality effectively.
Insomnia, Insufficient Sleep, and Poor Sleep Quality Adversely Affect Your Health
When your biological clock is out of sync, you stay awake despite feeling drowsy, or you cannot unwind during downtime and wake up early for work, the sleep quality inevitably deteriorates. For those with conditions like sleep apnea, reduced oxygen uptake during sleep can disrupt the expression of genes responsible for regulating sleep, leading to frequent nighttime awakenings and shorter sleep durations. These may result in insomnia, insufficient sleep, and poor sleep quality, leaving the body fatigued and unrefreshed and impairing learning and work performance.
The circadian rhythm works with the homeostatic system, which maintains bodily equilibrium, including temperature regulation, blood pressure, electrolyte, and neurotransmitter balances. Together, these systems ensure that humans remain alert during the day and naturally feel sleepy at night, responding to sunlight or ambient light. These two systems are in sync to create ideal intervals for resting and waking up.
Plotting data from both systems on a graph reveals that our alertness peaks between 6-8 a.m. and gradually declines throughout the day, with sleepiness most pronounced around 8 p.m. If we delay sleep during this drowsy period – such as by continuing important work or having a long phone call -- by the time it is 10 p.m., the feeling of sleepiness often subsides. This disruption can interfere with the circadian rhythm, potentially leading to insomnia.
That is why maintaining a consistent bedtime and wake-up schedule is essential. It can preserve the natural synchronization of the circadian rhythm and homeostasis, minimizing sleep-related issues and reducing the risk of sleep disorders.
How Can Shift Workers Adjust Their Circadian Rhythm?
Once you understand how sleep is regulated, you can modify your sleep schedule using light exposure and melatonin, a hormone naturally produced by the brain after sunset, which induces drowsiness. The synthetic form of melatonin is available to treat conditions such as insomnia.
Light exposure is an effective way to adjust sleep timing. To promote earlier sleep, seek morning sunlight. To stay awake later or prevent sleep at night, expose yourself to light in the evening. For night-shift workers, it is crucial to remain in a well-lit environment. A light intensity of at least 119 lux is required to modulate the circadian rhythm and homeostasis, enhancing alertness and suppressing sleepiness.
Melatonin helps induce sleep by naturally rising about two hours before bedtime. To adjust sleep timing, take 2–3 mg of melatonin approximately two hours before your intended bedtime. Additionally, keep the sleeping environment serene and quiet.
Adjusting Room Temperature for Better Sleep
As mentioned earlier, temperature plays a role in regulating circadian rhythm and homeostasis. Maintaining a proper room temperature can considerably enhance sleep quality. Studies conducted abroad suggest that 23°C is ideal in temperate regions, while 25°C may be more comfortable for those living in Thailand.
Another effective method involves modulating body temperature. Taking a warm shower before bed raises the body temperature. Upon entering a cool, air-conditioned room, the sudden drop in body temperature mirrors the bodily natural cooling process as it prepares for sleep, making it easier to fall asleep quickly.
Another factor that pertains not to the body temperature but the state of mind is the importance of organizing thoughts and easing anxiety. If your mind feels overwhelmed, consider streamlining your thoughts by writing them down on paper. This practice can help you organize and declutter your mind, reducing restlessness and worry before bedtime.
Sleeping issues should not be taken lightly and left unresolved, as they can significantly impact quality of life. Additionally, they may lead to health complications that could be life-threatening. One should consult a sleep medicine specialist for diagnosis and appropriate treatment planning.
