Why is bright light at night bad for sleep?


Bright light exposure at night is detrimental to sleep quality due to its impact on the body's release of melatonin, a hormone that regulates sleep-wake cycles. Here's why:

  • Melatonin Suppression: Bright light inhibits the secretion of melatonin, also known as the "hormone of darkness," which signals to the brain that it's night and time to sleep. Exposure to bright lights before bedtime can delay this signal, keeping you awake longer 1.

  • Circadian Rhythm Disruption: The circadian rhythm, which helps regulate sleep patterns, is sensitive to light. Exposure to bright lights at night can shift the timing of sleep, making it harder to fall asleep and wake up at your intended times 1.

  • Neurological Impact: There are specific neurons in the eye that are sensitive to light and play a role in circadian regulation. Bright overhead lights at night can mimic sunlight, which disrupts the brain's natural signaling for sleep 1.

To support healthy sleep patterns, it's recommended to minimize exposure to bright and especially overhead lights during late evening hours. Opt for dimmer, warmer lights to prepare for sleep adequately 2.

Optimize Your Sleep

Andrew explains the importance of avoiding bright artificial lights between 10:00 p.m. and 4:00 a.m. to improve sleep quality. He also recommends using low lights at night and bright artificial lights during the day to optimize sleep-wake cycles. Additionally, viewing evening sunset light can offset some of the negative effects of artificial light at night.

Huberman Lab

Sleep Toolkit: Tools for Optimizing Sleep & Sleep-Wake Timing | Huberman Lab Podcast #84