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Skeptic Check: Blue Light Special

June 29, 2026 · 59 min

Show notes

Many of us know the feeling: we intend to go to bed but pull out our phones for one last scroll. Setting them aside hours later, we’re wide awake, unable to fall asleep. For years, scientists have singled out blue light emitted from our devices as the key culprit behind our post-scrolling insomnia, but the scientific consensus is shifting. Although blue light signals to brains that its daytime, surprising new research suggests that our glowing screens may play a smaller role than previously thought.

We present the fascinating science around biological mechanisms of sleep and wakefulness, why circadian rhythms have more in common with your grandfather’s clock than you might think, and why scientists who question the role of blue light in causing nighttime restlessness, still don’t let our phones off the hook completely.

Guests:

Michael Gradisar – clinical psychologist and sleep researcher, former professor at Flinders University in Australia. Currently serves a head of Sleep Science at Sleep Cycle, a sleep tracking app company

Jay Dunlap – geneticist and molecular geneticist at the Geisel School of Medicine at Dartmouth who works the molecular basis of circadian rhythms

Mariana Figueiro – photobiologist, Director of the Light and Health Research Center and Professor of Population Health Science and Policy at the Icahn School of Medicine at Mount Sinai

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