Dr. Andrew Huberman, Ph.D. is a Professor of Neurobiology and Ophthalmology at Stanford University School of Medicine. His lab focuses on neural regeneration, neuroplasticity, and brain states such as stress, focus, fear, and optimal performance.
Andrew Huberman discusses how our brain and body track time, the role of hormones in time perception, and how our bodies are oriented in time. He also provides actionable tools to enhance productivity, creativity, and relationships.
Host: Andrew Huberman (@hubermanlab)
Entrainment: the way in which internal processes are linked to the external world
We have nerve cells in our body marking the passage of time via light processing
Light is a powerful modulator of melatonin & actually inhibits melatonin – if you view light in the middle of the night (e.g., turn on a bathroom light) your melatonin levels will crash
As daylight changes, our hormones change – meaning perception of time is conscious and unconscious
In the spring when the days are getting longer, melatonin is decreased and gives the feeling of more energy
In the winter when the days are getting shorter, melatonin is increased and can reduce energy
Our bodies are so tied to sunlight and the environment, even more testosterone and estrogen are produced when days are longer
No one can escape the circadian time cycle – we will all be active in some periods and sleep in others
Every cell in our body has a 24-hour cycle and are entrained to the outside cycle
Disruptions in circadian entrainment increase cancer risk, mental issues, decrease wound healing, disrupt physical performance, hormone disruption, and other similarly poor health outcomes
How to realign or “entrain” circadian clock:
  • 1. View 10-30 minutes of sunlight within an hour of waking,
  • 2. Get as much bright light as you can throughout the day and as little light as you can in the evening,
  • 3. Avoid sunglasses if you can do so safely,
  • 4. Exercise at a consistent time of day
  • 5. Eat at consistent times throughout the day
Disruption of circadian clocks also disrupts perception of shorter time intervals
Sleep is generally broken up into 90-minute cycles called the ultradian rhythm
Earlier in the night, we have slow-wave sleep (non-REM) and less REM sleep
For every 90 minute cycle, REM occupies more time – the more sleep you get, the more REM you have
The 90 minute time block continues throughout the day and governs our focus and brain cycles even during waking hours – after 90 minutes there’s a drop in ability to focus on hard things
When does the 90-minute cycle begin after waking? You can initiate them whenever you want (unlike circadian rhythm which is hardwired) – when you want to start, tune out all distractions and get to work
You must take breaks between 90-minute cycles of productivity (focused, hard work), not exceeding 2-3 per day
Three forms of time perception: (1) current interval timers which signal passage of time as quickly or slowly; (2) prospective timers measuring forward time; (3) retrospective time measuring how you measure time in the past  
Dopamine and serotonin modulate perception of time
The more dopamine and epinephrine released in the brain, the more we overestimate how much time has passed
Dopamine and norepinephrine increase frame rate in the brain and lead us to overestimate the amount of time that has passed
Serotonin causes us to underestimate how much time has passed
Throughout the 24 hour cycle, there are varying amounts of how much dopamine and serotonin are present in blood and body depending on the time of day
In the first half of the day dopamine and norepinephrine are elevated in the brain, body, and bloodstream; in the second half of the day serotonin levels increase
We should do the hardest task in the first half of the day because we can leverage the dopamine system and problem solve more effectively with increased frame rates
When we haven’t slept well, our sense of the passing of time is disrupted
Trauma or traumatic events can lead to “overclocking” where we perceive things in slow motion which can be imprinted in the brain and the firing of neurons is stamped
“Overlocking is when the frame rate is so high that a memory gets stamped down and people have a hard time shaking that memory and emotions associated with that memory.” – Dr. Andrew Huberman
  • Trauma treatment is designed to change frame rate so it slows down such that the person can control (more on trauma coming in future episodes)
There is a paradoxical relationship between perception of time in the moment and retrospective time: if you experience something fun (and increases dopamine) it will feel like it goes by very fast; in retrospect, that experience will seem like a longer time
  • The opposite is also true: we will recall low dopamine or long experiences as short in retrospect
Dopamine and increases in dopamine are induced by spontaneous blinking
How to leverage blinking for time perception: every time we blink we increase our perception of time – if you want to slow down your perception of time, blink less – conversely if you want to speed up your perception of time, blink more
Cold exposure: cold exposure increases dopamine release 
Relationships and social interactions: the more novel experiences we have in a place or with a person, the more we feel we know the place (or person) and the longer we feel we’ve been there or known them
The more novelty you experience with someone, the better you feel you know them even though the amount of time is fixed
Recommended reading: Your Brain Is A Time Machine by Dean Buonomano