The Importance of Sunlight for Sleep

What is Your Circadian Rhythm?

Your circadian rhythm is the biological clock that regulates the timing of your cellular activities. Interestingly, each individual cell has its own clock, and these clocks sometimes fall out of sync. This desynchronization can cause issues such as jet lag, where you might feel energetic when you want to sleep and tired when you need to work. This happens because your biological clock remains set to your previous time zone, providing energy at times when it was previously needed. Maintaining synchronization among all your cellular clocks is crucial for high-quality sleep, optimal immune function, and sustained focus.

Morning Sunlight Tunes Your Circadian Rhythm

One of the best ways to tune your circadian rhythm is morning sunlight. It is vital that you get bright light in the mornings, preferably sunlight. To get sufficient sunlight, look towards the sun but not directly at it for 5-15 minutes. During cloudy days spend more time outside doing this practice as less sunlight available. Don’t wear sunglasses as significantly less light will pass through them. However, eyeglasses and contacts are okay.

The light from the sun triggers the nerves in your eyes to tell your brain to wake you up. In every 24 hour period your body needs to have a cortisol spike and keeping that spike earlier in the day gives you more focus during day time and makes you sleepier at night. Additionally, the signal to your brain starts a 16 hours timer where, once completed, melatonin will be released, drawing your brain and body to sleep. In addition, morning sunlight tunes each cell’s clock to the same time, giving you better mood, brain function, and sleep.

Managing Light Exposure Throughout the Day to Optimize Circadian Rhythm

During the day it is vital that you have bright overhead lights on. Keeping these lights shining and going into your eyes will constantly remind your brain that it is day and that you need energy. Thus, you will experience better focus, energy, and mood. But, towards the evening, try to dim your lights and keep them below eye level. Bright, overhead lights in the late afternoon messes up your circadian rhythm. When you’re reaching the end of that 16 hour timer, your brain is expecting lower and dimmer light. Thus, these bright lights will not allow your brain to transition to night time, and your brain will go into overdrive. A good way to prevent this is going for an evening walk. The contrast of the yellow and orange wavelengths against the dark blue will signal to your brain that it is the evening. This will serve as a point of reference to your brain, keeping your circadian rhythm in check.

Citations

The Benefits of Morning Sunlight & How to Make it a Habit

Mead MN. Benefits of sunlight: a bright spot for human health. Environ Health Perspect. 2008 Apr;116(4):A160-7. doi: 10.1289/ehp.116-a160. Erratum in: Environ Health Perspect. 2008 May;116(5):A197. PMID: 18414615; PMCID: PMC2290997.

Jet lag disorder

Using Light (Sunlight, Blue Light & Red Light) to Optimize Health | Huberman Lab Podcast #68