Dr. Matt Walker: Using Sleep to Improve Learning, Creativity & Memory | Huberman Lab Guest Series

KEYPOINTS

• 01

  You need sleep before learning to absorb new information

  In Walker's brain-scanning study, people kept awake all night showed a 40% deficit in forming new memories compared with those who slept. Replications with visual and textbook-style material put the deficit at 20–40%. Animal studies show why: sleep-deprived animals' hippocampus, the brain's short-term memory store, becomes 'stubborn' and won't form new synaptic connections.

• 02

  A nap can refresh your capacity to learn

  Two groups learned a large set of facts at noon, then learned a new set at 6 p.m. The group that stayed awake learned progressively worse. The group given a 90-minute nap (enough for a full cycle of non-REM and REM sleep) showed no decline, a difference of about 20%. Sleep spindles, short bursts of activity in non-REM sleep, predicted how much learning ability was restored. Walker compares the hippocampus to a USB stick that sleep empties for new files.

• 03

  You also need sleep after learning to keep memories

  Cramming gets material through tomorrow's exam, but a month later almost none of it remains, because without sleep it never moves into long-term storage. Walker's rule is to sleep both the night before and the night after learning something important.

• 04

  Sleep improves physical skills without extra practice

  People practiced typing a number sequence (such as 4-1-3-2-4). Twelve hours awake brought no improvement. After a night's sleep the same people were about 20% faster and nearly 37% more accurate. 'Practice with a night of sleep makes perfect.' The gain tracks stage 2 non-REM sleep and its spindles, and naps produce it too, so it's caused by sleep rather than by nighttime.

• 05

  Time learning to your circadian rhythm

  There are good learning windows in the morning and again after the post-lunch dip, which usually falls somewhere between 1 and 4 p.m. and lasts 60–90 minutes. Many people get a 'second wind' around 9 p.m. that lasts roughly 45–70 minutes. Walker advises riding it out with dim lights and a calm wind-down rather than taking it as a sign you aren't tired.

• 06

  Short sleep hurts athletic performance and motivation

  Under 6 hours of sleep reduces peak muscle output and vertical jump, and time to exhaustion can fall by up to 30%. Perhaps most striking, it lowers the motivation to exercise at all. The relationship works in both directions: daytime exercise deepens sleep that night.

• 07

  Dieting on too little sleep costs muscle instead of fat

  When you diet while underslept, you still lose weight, but almost 60% of it can come from lean muscle rather than fat. As Walker puts it, you keep what you want to lose and lose what you want to keep.

• 08

  REM sleep fuels creative connections

  In Walker's anagram study, people woken from REM sleep solved about 30% more puzzles than when woken from non-REM sleep, and they solved them in a looser, more intuitive way, with answers seeming to just pop out. Non-REM sleep strengthens individual facts, while REM links distant ideas, which is the overnight alchemy behind 'sleeping on a problem.'