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 saving time leads to outsized effects on our biology because our cells and circadian clocks integrate across many days. He offers precise tools to rapidly adjust to jet lag, 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 an up-to-date list of our current sponsors, please visit our website: https://www.hubermanlab.com/sponsors. Previous sponsors mentioned in this podcast episode may no longer be affiliated with us. Social: Instagram - https://www.instagram.com/hubermanlab Twitter - https://twitter.com/hubermanlab Facebook - https://www.facebook.com/hubermanlab Website - https://hubermanlab.com Newsletter - https://hubermanlab.com/neural-network Samer Hattar: Twitter: https://twitter.com/samerhattar Instagram: https://www.instagram.com/samerhattar Wikipedia: https://en.wikipedia.org/wiki/Samer_Hattar Links: Graphical Explanation of Temperature Minimum for Overcoming Jetlag: https://www.instagram.com/tv/CKWiRVJHVwC/ Timestamps: 00:00:00 Introducing Dr. Samer Hattar, Ph.D. 00:02:17 Sponsors: ROKA, InsideTracker, Magic Spoon 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 Jet Lagged 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 Jet Lag: 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 Please note that The Huberman Lab Podcast is distinct from Dr. Huberman's teaching and research roles at Stanford University School of Medicine. The information provided in this show is not medical advice, nor should it be taken or applied as a replacement for medical advice. The Huberman Lab Podcast, its employees, guests and affiliates assume no liability for the application of the information discussed.