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Matthew Walker

PhD · Professor of neuroscience and psychology, UC Berkeley · founder and director of the Center for Human Sleep Science · author of Why We Sleep

Go-to expert for: why sleep matters for health

Who and why

Matthew Walker is a sleep scientist and professor at the University of California, Berkeley, where he founded and leads the Center for Human Sleep Science. His lab studies how sleep affects memory, the ageing brain and diseases such as Alzheimer's. His 2017 book Why We Sleep and his 2019 TED talk made him one of the best-known public voices on sleep.

Why it matters after 50: Deep sleep tends to decline with age, and his research links that loss to poorer overnight memory in older adults. Protecting sleep quality is one of the simplest things you can do for brain health later in life.

What Walker recommends

  • Keep a regular sleep schedule, going to bed and getting up at about the same time every day.Some evidence
  • Get daylight every day, ideally at least 30 minutes, and preferably in the morning.Some evidence
  • Cut back on caffeine and nicotine, and limit alcohol in the evening.Some evidence
  • Finish hard exercise about 2 to 3 hours before bed, and stop drinking fluids about 2 hours before bed to reduce night-time bathroom trips.Personal habit
  • If you cannot fall asleep after about 25 to 30 minutes, get up and do something calm until you feel sleepy, so your bed stays linked with sleep.Strong evidence
  • Most adult guidelines recommend 7 to 9 hours. Large studies find the lowest death rates around 7 hours, so there is no need to panic about an occasional short night.Note

Signature: Sleep and the ageing brain

His lab showed that older adults lose much of their deep (slow-wave) sleep, that this loss is tied to shrinking of the frontal brain, and that it goes with weaker overnight memory. He later popularised this work, and sleep science in general, in Why We Sleep.

In your plan

Choose him for sleep: a fixed sleep window, and hard evening sessions finish 2–3 hours before bed.

Build my mix

Research and honest caveats

Deep sleep, brain shrinkage and memory in older adults

Older adults had much less deep sleep than young adults, linked to frontal brain atrophy, and remembered less of what they had learned the night before.

Mander, Walker et al., Nature Neuroscience, 2013

  • In 2019 researcher Alexey Guzey published a detailed critique arguing that Why We Sleep overstates several claims, and he and statistician Andrew Gelman later faulted a graph in the book for leaving out data that did not fit. Walker acknowledged that his claim of a WHO-declared 'sleep-loss epidemic' was misremembered and posted replies to readers' questions, but the book's most dramatic statistics are best read with caution.

Career highlights

  1. 1999PhD in neurophysiology, Newcastle University
  2. 2004Assistant professor of psychiatry, Harvard Medical School, before moving to UC Berkeley
  3. 2017Published Why We Sleep, an international bestseller
  4. 2019Gave the TED talk Sleep is your superpower

Sources