In this episode, I discuss how our brain and body track time and the role that neurochemicals, in particular dopamine and serotonin, but also hormones such as melatonin, allow us to orient ourselves in time. I review the three types of time perception: of the past, of the present, and the future, and how dopamine and serotonin adjust both our perception of the speed of the passage of time and our memory of how long previous experiences lasted. I also discuss circannual entrainment, which is the process by which our brain and body are matched to the seasons, and circadian (24 hours) entrainment, both of which subconsciously adjust our perceived measurement of time. I explain the mechanisms of that subconscious control. And I cover the ultradian (90 minutes) rhythms that govern our ability to focus, including how to track when these 90-minute rhythms begin and end for the sake of work and productivity. I include ten tools based on the science of time perception that you can apply to enhance productivity, creativity, and relationships in various contexts.  For the full show notes, visit hubermanlab.com. Thank you to our sponsors AG1 (Athletic Greens): https://athleticgreens.com/huberman LMNT: https://drinklmnt.com/huberman Thesis: https://takethesis.com/huberman Supplements from Momentous https://www.livemomentous.com/huberman Timestamps (00:00:00) Introducing Time Perception, Note on Fasting & Supplements (00:05:28) Sponsors: AG1, LMNT, Thesis, Momentous (00:09:25) Entrainment, Circannual Entrainment, Melatonin (00:13:20) Seasonal Oscillations in Testosterone & Estrogen, Tool 1 (00:16:06) Circadian Timing, Tools 1, 2, 3 (for Circadian Entrainment) (00:21:13) Tool 4: Timing Physical Activity; Tool 5: Timing Eating Window (00:23:00) When Circadian Entrainment is Disrupted, Time Perception Suffers (00:25:00) Tool 6: Ultradian (90min) Cycles & Focus (00:31:42) Our Sense of the Passage of Time: Present, Prospective, Retrospective (00:34:40) Dopamine (& Nor/epinephrine) Lead to Time Overestimation; Frame Rate  (00:37:18) Serotonin & Time Underestimation; Decreased Frame Rate (00:39:10) Dopamine vs. Serotonin Across the Day; Tool 7: When to Do Rigid vs. Creative Work (00:42:38) Example of Tool 7 (00:43:38) How Sleep Deprivation Degrades Performance (00:44:38) Trauma, “Over-clocking” & Memories; Adjusting Rates of Experience (00:50:04) Why Trauma Involves Dopamine & Epinephrine, Arousal (00:51:03) Dopamine, Spontaneous Blinking & Time Perception; Tool 8 (00:53:38) Deliberate Cold Exposure, Dopamine, Tool 9: Adjusting Frame Rate in Discomfort (00:56:30) Fun “Feels Fast” BUT Is Remembered as Slow; Boring Stuff “Feels Slow,” Recall As Fast (01:00:54) Retrospective Time, Context Variation & Enhanced Bonding with Places & People (01:03:00) Dopamine Release Resets the Start of Each Time Bin on Our Experience (01:07:40) Habits & Time Perception; Tool 10 (Setting Functional Units of Each Day) (01:11:58) Synthesis & Book Suggestion (Your Brain Is a Time Machine by D. Buonomano) (01:12:27) Supporting the HLP: Subscribe, Instagram, Supplements Title Card Photo Credit: Mike Blabac Disclaimer