Why is morning sunlight important?

Morning sunlight is essential for several physiological processes. According to Andrew Huberman, when morning sunlight enters the eyes, it activates neurons that signal it’s daytime and time to be alert. This sets off numerous biological cascades in cells and organs throughout the body, including the brain, liver, gut, and heart. Additionally, exposure to morning sunlight induces a healthy rise in cortisol levels from the amygdala, promoting wakefulness and supporting a robust immune system. This cortisol spike should occur early in the day, and its timing can be regulated by when you are exposed to bright light, with the most effective time being early in the morning 1.

The benefits of morning sunlight include setting your circadian rhythms correctly, which affects your mood, sleep patterns, and metabolism. Even on cloudy days, outdoor light is far brighter and more effective for these processes than indoor light. Morning light exposure helps suppress melatonin that might be present upon waking, interacts with the adenosine system to help you feel more alert, and prepares your body to fall asleep about 16 hours later 2. It's recommended to practice getting sunlight exposure at least 80% of the days and to extend the exposure if missed a day 2.

Additionally, Dr. Samer Hattar and Andrew Huberman discuss the role of morning sunlight in adjusting the circadian rhythm and improving sleep quality. Intensity and duration of light exposure are important for regulating the circadian system 3. Overall, morning sunlight viewing is considered a powerful stimulus for wakefulness throughout the day and has a positive impact on the ability to fall and stay asleep at night 4.