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 *Follow Huberman Lab* Instagram: https://www.instagram.com/hubermanlab Threads: https://www.threads.net/@hubermanlab X: https://twitter.com/hubermanlab Facebook: https://www.facebook.com/hubermanlab TikTok: https://www.tiktok.com/@hubermanlab LinkedIn: https://www.linkedin.com/in/andrew-huberman Website: https://www.hubermanlab.com Newsletter: https://www.hubermanlab.com/newsletter *Dr. Samer Hattar* X: https://x.com/samerhattar Instagram: https://www.instagram.com/samerhattar *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