Why is morning sunlight important?


Morning sunlight is crucial for regulating the body's circadian rhythm, which controls our sleep-wake cycles and many other vital processes. Here are the key reasons why it's important, as discussed by and guests on the :

  1. Wakefulness and Sleep: Morning sunlight provides the most powerful stimulus for wakefulness during the day and has a positive impact on the ability to fall and stay asleep at night. It sets a timer within our brains that not only helps us wake up but also tells our body when it will be time to go to sleep later 1.

  2. Cortisol Regulation: Viewing morning sunlight triggers a healthy bump in cortisol, which is a hormone that increases wakefulness and promotes a healthy immune system. It's essential for this cortisol pulse to happen early in the day 2.

  3. Mood and Metabolism: Morning sunlight exposure can improve daytime mood, focus, and alertness, and also has profound positive effects on metabolism. Better sleep influenced by morning light might indirectly improve metabolism 3.

    Morning Sunlight Benefits

    Andrew explains the benefits of morning sunlight viewing and how it affects our physiology. Sunlight is the most powerful stimulus for wakefulness throughout the day and has a positive impact on our ability to fall and stay asleep at night. Artificial lights can replace sunlight before the sun is out, but not after it has risen.

    Huberman Lab

    Sleep Toolkit: Tools for Optimizing Sleep & Sleep-Wake Timing | Huberman Lab Podcast #84
  4. Duration and Intensity: Both the intensity and duration of exposure to morning sunlight are important. Even on a cloudy day, the outdoor light is far brighter than indoor lighting. If it's dim outside, a longer duration of exposure compensates for lower intensity 4.

  5. Circadian Alignment: Both exercise and sunlight are potent cues for circadian rhythm alignment. This helps keep our body's internal clock in sync with the earth’s 24-hour day, promoting better sleep at night 5.

  6. Non-visual Pathways: Specialized neurons in our eyes, which are not involved in forming images, convey the information that it is daytime to the suprachiasmatic nucleus (a key brain area for circadian regulation) to trigger the wake-up sequence for all the cells in our body 6.

  7. Melatonin Suppression: Morning light exposure suppresses melatonin levels, which may linger in our system upon waking, improving alertness 7.

It's recommended that we expose ourselves to morning sunlight, if possible, within the first hour of waking up, without sunglasses, to receive its full benefit 6.