In this episode, I host Dr. Samer Hattar, Chief of the Section on Light and Circadian Rhythms at the National Institute of Mental Health. Dr. Hattar is a world-renowned expert on how viewing light at particular times adjusts our mood, ability to learn, stress and hormone levels, appetite, and mental health. We discuss how to determine and use your individual light sensitivity to determine the optimal sleep-wake cycle for you. We also discuss how to combine your light viewing and waking time with the timing of your food intake and exercise in order to maximize mental and physical functioning. Dr. Hattar is credited with co-discovering the neurons in the eye that set our circadian clocks and regulate mood and appetite. He explains why even a small shift in daylight savings leads to outsized effects on our biking because of the way that our cells and circadian clocks integrate across many days. And he offers precise tools to rapidly adjust to jetlag, shift work, and reset your clock after a late night of work or socializing. This episode is filled with cutting-edge data on the biological mechanisms of human physiology and practical tools for people of all ages.

For the full show notes, visit hubermanlab.com.

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Timestamps

(00:00:00) Introducing Dr. Samer Hattar, Ph.D.

(00:02:33) Sponsors: AG1, LMNT

(00:06:15) Light, Circadian (24 hour) & Circannual (365 day) “Photoentrainment”

(00:14:30) Neurons in Our Eyes That Set Our Body Clocks: Similar to Frog Skin

(00:18:55) What Blind People See

(00:20:15) When, How & How Long to View Light for Optimal Sleep & Wakefulness

(00:30:20) Sunlight Simulators, Afternoon Light Viewing, Naps

(00:33:48) Are You Jetlagged at Home? Chronotypes & Why Early Risers Succeed

(00:38:33) How to Decide Your Best Sleep-Wake Schedule; Minimal Light Test

(00:42:16) Viewing Light in Middle of Day: Mood & “Light Hunger”

(00:44:55) Evening Sunlight; Blueblocker Warning

(00:48:57) Blue Light Is Not the Issue; Samer’s Cave; Complete Darkness

(00:53:58) Screens at Night

(00:56:03) Dangers of Bright Light Between 10 pm and 4 am: Mood & Learning

(01:01:05) The Tripartite Model: Circadian, Sleep Drive, Feeding Schedules

(01:05:05) Using Light to Enhance Your Mood; & The Hattar-Hernandez Nucleus

(01:07:19) Why Do We Sleep?

(01:08:17) Effects of Light on Appetite; Regular Light & Meal Times

(01:18:08) Samer’s Experience with Adjusting Meal Timing

(01:22:51) Using Light to Align Sleep, Mood, Feeding, Exercise & Cognition

(01:30:15) Age-Related Changes in Timing of Mental & Physical Vigor

(01:31:44) “Chrono-Attraction” in Relationships; Social-Rhythms

(01:33:40) Re-setting Our Clock Schedule; Screen Devices Revisited

(01:37:50) How Samer Got into the Study of Light

(01:39:33) Clock Gene mRNAs & More Accurate Biomarkers

(01:41:08) Light as Medicine

(01:42:48) ADHD (Attention-Deficit Hyperactivity Disorder)

(01:43:35) How to Beat Jetlag: Light, Temperature, Eating

(01:50:44) Vigor: The Consequence of Proper Timing

(01:52:15) Waking in the Middle of the Night: When Your Nightly Sleep Becomes a Nap

(01:54:10) Melatonin, Pineal Calcification

(01:55:25) Our Seasonal Rhythms: Mood, Depression, Lethargy & Reproduction

(01:59:08) Daylight Savings: Much Worse Than It Might Seem

(02:05:27) Eye Color & Sensitivity to Light, Bipolar Disorder

(02:09:28) Spicy Food, Genetic Variations in Sensory Sensitivity

(02:10:52) Synthesizing This Information, Samer on Twitter, Instagram

(02:13:00) Conclusions, Ways To Support the Huberman Lab Podcast & Research

Title Card Photo Credit: Mike Blabac

Disclaimer

Dr. Samer Hattar: Timing Your Light, Food, & Exercise for Optimal Sleep, Energy & Mood