Lesson Five: Support your sleep cycle and circadian rhythm

Our circadian rhythms are internal clocks that help our bodies “tell the time,” influencing when various biological processes should be active or at rest.

The suprachiasmatic nucleus (SCN), a group of around 20,000 nerve cells in the brain, controls our circadian rhythm. Light entering our eyes through the retina sends messages to the SCN, regulating our core body temperature and triggering various biological processes, such as:

  • Digestive system activity,
  • Hormone production,
  • Hunger levels,
  • Metabolism, and
  • Melatonin production — which determines sleepiness.

Circadian rhythmicity is also observed in many circulating hormones, immune cells, and cytokines. [1]

The power of our circadian clock

When our circadian clock maintains a steady rhythm, we wake up as it gets light outside and feel sleepy when darkness falls. Individual variations exist in how quickly our digestive system wakes up and when we feel most alert.

Our 24-hour circadian clock is key to maintaining the natural rhythm of our biological functions and anticipates environmental changes associated with daylight cycles. [2] Living in sync with nature, such as rising with the morning sunlight and sleeping when night falls, helps regulate light entering our SCN. Consistent sleep times also help entrain our body to specific wake and sleep times, benefiting other biological functions like digestion and liver function.

The role of hormone melatonin

Melatonin plays two roles in the circadian rhythm: entraining the rhythm to align with darkness and promoting sleep onset by increasing sleep drive and slowing down biological processes. [3] Supporting natural melatonin production involves maintaining a regular sleep-wake cycle and reducing exposure to unnatural blue light in the evening.

Importance of light

Light is a vital timekeeper for the biological system, influencing immune system modulation by the autonomic nervous system (ANS), which shows daytime rhythmicity. Light therapy can support melatonin fluctuations in people with sleep disorders and may help healthy heart rate variability (HRV), linked with sleep quality and ANS dysfunction. [4]

The blue light from smartphones, TVs, and other devices can suppress melatonin secretion, making sleep more difficult. Blue-blocking light glasses, such as TrueDark® Daylights glasses, can help filter the excess blue light from artificial sources, supporting better sleep.

In conclusion, understanding and supporting our circadian rhythm is crucial for overall well-being, especially regarding our sleep cycles. The SCN orchestrates various biological processes, including hormone production and melatonin levels, regulating sleepiness. Aligning our daily routines with natural light cycles can positively impact our circadian rhythm. The role of light, particularly the disruption caused by blue light from electronic devices, is significant. Implementing practical solutions like reducing nighttime screen use or using TrueDark® glasses to filter blue light can mitigate these effects. By respecting our circadian rhythm and adjusting our lifestyle, we can enhance our sleep quality and overall health.

References
[1] ‘Chronomics’ in ICU: circadian aspects of immune response and therapeutic perspectives in the critically ill.
[2] Melatonin and cortisol exhibit different circadian rhythm profiles during septic shock depending on timing of onset: a prospective observational study.
[3] The Role of Melatonin in the Circadian Rhythm Sleep-Wake Cycle.
[4] ‘Chronomics’ in ICU: circadian aspects of immune response and therapeutic perspectives in the critically ill.

Note: The article is intended for informational purposes. For medical advice or information about specific products, it's advised to consult with healthcare professionals or refer directly to the product manufacturers.