How does light affect hormones?


Light exposure significantly affects hormones, particularly those involved in regulating circadian rhythms and stress responses.

  1. Circadian Rhythm and Melatonin:
    Blue light exposure in the evenings can hinder melatonin production, a hormone that induces sleepiness. Melatonin levels rise towards evening naturally, but blue light has been shown to inhibit its production, thereby delaying sleep onset. Conversely, exposure to bright light in the morning helps reset the circadian clock, promoting wakefulness and improved sleep patterns at night 1 2.

  2. Cortisol:
    Bright light exposure also impacts cortisol levels, a hormone involved in stress response and inflammation regulation. For instance, a study indicated that exposing humans to 10,000 lux bright light for seven hours a day during the rising phase lowered their cortisol response when it is typically at its peak. This suggests that light exposure can modulate the body's stress response 2.

Rhonda Patrick emphasizes optimizing light exposure through practical adjustments, using lights that can switch from blue during the day to red during the evening to mimic natural light cycles. This approach helps support healthy circadian rhythms and hormonal balance, promoting better sleep and mood regulation 2.

Blue Light and Melatonin

Satchin explains how our body's circadian rhythms are affected by blue light and melatonin, and how our sleep and wake up time adjust to changing day length. He also talks about the discovery of melatonin and blue light receptors and how they sense light during the daytime or blue light from electrical lighting.

Found My Fitness

Dr. Satchin Panda on Circadian Insights into Exercise Timing, Melatonin Biology, and Peak Cognition