#135 - Two Windows: How Light Shapes your Sleep

Matt delves into how daily light exposure dictates our sleep quality and how improper lighting can derail perfect sleep hygiene. He explains that our brain's internal clock naturally drifts backward by 14 minutes daily, requiring a corrective signal like outdoor sunlight before 10:00 a.m. to act as a crucial biological anchor for timing the eventual release of sleep-regulating hormones like melatonin.

Moving to the evening, Matt unpacks how artificial lighting combats our biology by suppressing melatonin. Citing research by Dr. Michael Gradisar, he clarifies that standard room lighting biologically disrupts circadian rhythms far more than smartphone screens, which instead harm sleep by behaviorally engaging us past bedtime. Ultimately, Matt offers a simple, cost-free framework for better sleep: seek morning daylight and keep evening environments below 10 lux.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

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As always, if you have thoughts or feedback you’d like to share, please reach out to Matt:

Matt: Instagram @drmattwalker, X @sleepdiplomat,

YouTube: https://www.youtube.com/channel/UCA3FB1fOtY4Vd8yqLaUvolg