This is episode 3 of a 6-part special series on sleep with Dr. Matthew Walker, Ph.D., a professor of neuroscience and psychology at the University of California, Berkeley, and leading public educator about the role of sleep in health, disease and performance.  We explain how our sleep architecture changes as we age. We also cover how childhood development and aging affect sleep biology and needs. We also discuss whether polyphasic sleep (multiple short sleep periods) is beneficial.  Then, we discuss naps, including their positive benefits, individual variability, those who should not nap, and alternative rest states like non-sleep deep rest. Dr. Walker shares protocols to optimize nap duration, timing and effectiveness. We also explore the effects of caffeine on sleep and other health aspects, as well as the optimal timing for caffeine intake. This episode describes many actionable science-based tools for optimizing sleep, naps and caffeine use for better health and performance. The next episode in this special series explores the relationship between sleep, memory, and creativity. For show notes, including referenced articles and additional resources, please visit hubermanlab.com. Thank you to our sponsors AG1: https://drinkag1.com/huberman BetterHelp: https://betterhelp.com/huberman LMNT: https://drinklmnt.com/huberman Waking Up: https://wakingup.com/huberman Eight Sleep: https://eightsleep.com/huberman Momentous: https://livemomentous.com/huberman Timestamps (00:00:00) Sleep Structure (00:01:29) Sponsors: BetterHelp, LMNT & Waking Up (00:05:42) Sleep Phases & Lifespan (00:11:58) Sleep Stages & Lifespan, Sleep Paralysis & Animals (00:20:19) Adults & Biphasic Sleep, Modern Society (00:25:14) Chronotype, Circadian Rhythms & Biological Flexibility (00:29:07) Genetics & Chronotype (00:31:42) Sponsor: AG1 (00:32:55) Biphasic Sleep, Adults; Body Position & Sleepiness (00:40:09) Naps, Positive Benefits, Nighttime Insomnia (00:49:38) Tool: Optimal Nap: Duration & Timing; Grogginess (00:58:15) Nap Capacity, “Liminal” States & NSDR (01:07:37) NASA Nap Culture, Power Naps (01:11:49) Sponsor: Eight Sleep (01:12:50) Tools: Nap Timing, “Fragile” Nighttime Sleep; On-Off-On Protocol (01:18:57) Avoiding Naps: Insomnia, Aging & Sleep Quality Decline (01:28:20) Caffeine, “Nappuccino”; Hot Drinks (01:38:28) Adenosine Clearance, Sleep  (01:43:10) Tool: Delaying Caffeine, Afternoon Crash, Sleep Quality (01:49:06) Caffeine, Health, Antioxidants; Caffeine Tolerance & Alcohol (01:56:54) Tool: Nap “Enhancements”, Caffeine, Light & Face Washing (02:04:33) Polyphasic Sleep, Adverse Effects (02:12:43) Sleep Deprivation & Car Crashes; Polyphasic Sleep (02:16:49) Zero-Cost Support, Spotify & Apple Reviews, Sponsors, YouTube Feedback, Momentous, Social Media, Neural Network Newsletter Disclaimer