How to regulate the circadian (internal body clock) rhythm for improved health?

From the Guidelines

To hack your circadian rhythm for better health, prioritize establishing a consistent sleep schedule, strategically timed light exposure, and a relaxing evening routine, as these practices have been shown to improve sleep quality and overall health outcomes, as supported by recent studies 1.

Key Recommendations

• Establish consistent sleep and wake times every day, including weekends, to regulate your body's internal clock.
• Get bright light exposure within the first hour of waking, ideally natural sunlight for 10-30 minutes, to signal your brain it's daytime, as shown to be effective in phase advancing the melatonin circadian rhythm in young adults 1.
• Limit blue light exposure from screens in the evening by using blue light filters or wearing amber glasses 2-3 hours before bed, as short-wavelength light exposure is associated with increased melatonin suppression relative to long-wavelength light exposure in adolescents and adults 1.
• Create an evening wind-down routine that includes dimming lights and engaging in relaxing activities like reading or gentle stretching, to help regulate hormones like melatonin and cortisol that control your sleep-wake cycle.
• Keep your bedroom cool (65-68°F), dark, and quiet for optimal sleep quality, as a sleep-conducive environment is essential for improving sleep outcomes.
• Time your meals within a 10-12 hour window during daylight hours, avoiding large meals close to bedtime, to help regulate your body's internal clock and improve overall health.
• Exercise regularly, preferably in the morning or afternoon, as evening workouts can disrupt sleep for some people, and morning physical activity is known to advance circadian phase 1.
• If you need to shift your rhythm, make gradual adjustments of 15-30 minutes per day, as sudden changes can be challenging for your body to adapt to.

Supporting Evidence

• A 2022 study published in Sleep Medicine Reviews found that morning light therapy, combined with cognitive-behavioral therapy, can effectively phase advance the melatonin circadian rhythm in adolescents and young adults with delayed sleep-wake phase disorder (DSWPD) 1.
• The American Academy of Sleep Medicine clinical practice guideline for the treatment of intrinsic circadian rhythm sleep-wake disorders suggests that strategically timed melatonin and light therapy can be effective treatments for DSWPD and other circadian rhythm disorders 1.
• Research has shown that the human circadian system is most sensitive to short wavelength blue light (~480 nm), and that timed light exposure can shift circadian timing, leading to improved sleep outcomes and overall health 1.

From the FDA Drug Label

The FDA drug label does not answer the question.

From the Research

Hacking Your Circadian Rhythm for Better Health

To hack your circadian rhythm for better health, consider the following strategies:

• Use melatonin supplements to promote sleep and correct circadian phase shifts, as suggested by studies 2, 3, 4, 5
• Administer melatonin in the evening to advance the phase of the circadian clock, or in the morning to delay it, as shown in studies 3, 5
• Use low-dose melatonin treatment to promote sleep onset and maintenance without changing sleep architecture, as recommended by studies 3, 4
• Be cautious of high melatonin doses (over 0.3 mg) that may cause side effects and disrupt the circadian system, as warned by study 3
• Consider bright light therapy (BLT) as an alternative or complementary treatment for circadian rhythm disorders, as mentioned in study 6

Melatonin and Circadian Rhythms

Melatonin plays a crucial role in regulating human circadian rhythms and sleep, as evidenced by studies 2, 3, 4, 5, 6

• Melatonin is a reliable phase marker of the master circadian clock located in the suprachiasmatic nucleus (SCN), as stated in study 4
• Melatonin reinforces nighttime physiology, including timing of the sleep-wake cycle and other circadian rhythms, as explained in study 4
• Melatonin acts through two high-affinity membrane receptors (MT1 and MT2) with distinct distribution patterns, as described in study 4

Therapeutic Applications

Melatonin and its analogs have potential therapeutic applications in treating sleep disorders and other circadian disorders, as suggested by studies 2, 3, 4, 5, 6

• Exogenous melatonin can act as a soporific agent, a chronohypnotic, and/or a chronobiotic, as described in study 5
• Melatonin treatment can be helpful for individuals with low melatonin production, which can be established by measuring individual blood or saliva melatonin levels, as recommended by study 3