#01 What is Sleep?

Episode 01:  HighlightsHuman sleep has been separated into two main types: Non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleepNREM sleep is further divided into four stages, with each stage increasing in their depth of sleepREM sleep is named this way because of the bizarre, horizontal, shuttling eye movements that occur underneath your eyelids during this stage of sleepREM sleep is the principal stage in which we dream, although it can occur in the other stages as wellNREM and REM sleep play out in a battle for brain domination throughout the nightThis cerebral war is going to be won and lost every 90 minutes, creating the standard cycling architecture of sleep for humansOther species may have a slightly different NREM to REM cycles, with birds experiencing a cycle that only lasts about 4-5 minutes, and giraffes about 24 minutesDuring NREM sleep, we see bursts of deeply powerful brain waves that flow over your cortexWe also see sleep spindles, which are short, synchronous bursts of electrical brain wave activity that last for about 1-1.5 secondsAbout 60-70 minutes into your first sleep cycle, your brain starts to rise up again into later stages of NREM sleep, then pop into a short REM sleep period, back to NREM sleep, then returning to REM sleep once againYour brain goes through this cycle every 90 minutesWhat changes is the ratio of NREM to REM sleep as you move through the night, with your sleep cycle comprised of more REM sleep during the second half of the nightIf you wake up two hours earlier than usual, you aren’t just losing 2 hours of sleep - you could be losing 50, 60, or even 70% of your REM sleepAll stages of sleep are critical and perform different functions for the brain and body at different times of nightEpisode Sponsor:

This episode is sponsored by Athletic Greens, who are providing a discount and free product if you use the link above. Athletic Greens is a comprehensive daily nutritional beverage containing 75 vitamins, minerals, and whole food-sourced ingredients, including a multivitamin, multimineral, probiotic. So, head on over to www.athleticgreens.com/mattwalker and get a free year supply of Vitamin D and 5 free travel packs today.

Feedback:

Please visit Matt on Instagram and tell him what he can be doing to make these podcasts better, and let him know what topics you want him to cover next!  Links:

Brain Basics: Understanding Sleep | National Institute of Neurological Disorders and Stroke

Music credit:

By the incredible, Kai Engel (aka Anton Fedchenkov).