Essentials: Timing Light for Better Sleep, Energy & Mood | Dr. Samer Hattar

Andrew Huberman

Aug 21, 2025

Episode description

In this Huberman Lab Essentials episode, my guest is Dr. Samer Hattar, PhD, the Chief of the Section on Light and Circadian Rhythms at the National Institute of Mental Health.

We discuss how light powerfully shapes mood, sleep, appetite, learning and overall mental health by aligning—or misaligning—our internal circadian clock. We explain practical protocols to support your circadian rhythm, including morning sunlight exposure, dim evening lighting and regular mealtimes. We also discuss strategies to manage jet lag, limit evening screen use, ease seasonal depression and improve focus by syncing light, sleep and food with natural biological rhythms.

Episode show notes: https://go.hubermanlab.com/dKJ2cZQ

Huberman Lab Essentials are short episodes focused on essential science and protocol takeaways from past full-length Huberman Lab episodes. Watch the full-length episode: https://youtu.be/oUu3f0ETMJQ

Watch more Huberman Lab Essentials episodes: https://youtube.com/playlist?list=PLPNW_gerXa4OGNy1yE-W9IX-tPu-tJa7S

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*Dr. Samer Hattar*
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*Timestamps*
00:00:00 Samer Hattar
00:00:27 Light, Circadian Clock vs Solar Day, Sleep-Wake Cycle
00:03:20 Eyes, Photoreceptors & Light Entrainment, Blindness, Sleep
00:06:13 Morning Light, Artificial Lights, Tool: Morning Sunlight Exposure
00:08:28 Jet Lag Without Traveling, Sleep Issues, Screens, Staying Indoors
00:09:18 Chronotypes, Intrinsic Circadian Rhythms
00:11:10 Afternoon & Evening Light, Tools: Dimming Lights, Reduce Screen Use
00:13:00 Light Exposure & Effects on Stress, Mood & Learning, Tripartite Model
00:16:33 Light & Appetite, Tool: Regular Meal Times
00:19:42 Using Light to Improve Sleep, Mood & Mental Health
00:21:23 Jet Lag, Tools: Temperature Minimum; Eat on Local Schedule, Avoid Mismatched Light Exposure
00:24:55 Sleep Issues, Light-Dark Cycle
00:26:29 Seasonality, Seasonal Depression; Daylight Savings Time
00:29:46 Acknowledgements

Disclaimer & Disclosures: https://www.hubermanlab.com/disclaimer

Mindsip insights from this episode:

Avoid bright morning light when traveling east to protect your body clock

When traveling to a time zone many hours ahead, you must avoid bright morning light upon arrival to prevent shifting your body clock in the wrong direction.

#circadian

#sleep

Achieve perfect sleep despite blindness through non-visual light sensing

People who are completely blind to images can still have a perfect sleep-wake cycle because their eyes contain non-visual light-sensing cells that regulate their internal clock.

#circadian

#sleep

Utilize light to enhance mood regulation

Light regulates mood through a brain pathway that is completely separate from the one that controls your main circadian clock for sleep.

#light-therapy

#mood

Recognize hunger as a learned clock response

The feeling of hunger at specific mealtimes is a learned cue from your body's clock, not necessarily a sign of an immediate energy need.

#hunger

Avoid artificial light boxes for mood regulation in winter

Even if you live far north during a dark winter, it is personally suggested that you avoid using artificial light boxes to regulate your mood and clock.