Too much sleep: when long nights are a warning sign
Walker and Attia both address oversleeping, noting that very long sleep is often a marker of poor sleep quality, illness or depression. It corrects the idea that more time in bed is always better.
Is long sleep linked to worse outcomes? Show answer
Yes, on average. Mortality rises among very long sleepers, but the likely reason is that long sleep is a sign of something else.
What shape does the mortality data take, according to Peter Attia? Show answer
A curve. Mortality is higher at short sleep, falls as sleep increases, then ticks up again among very long sleepers.
Where does Matt Walker place the upturn? Show answer
Past about 10 to 11 hours of sleep. Risk also rises below seven hours.
What is the leading explanation for the upturn? Show answer
Illness. Sick people sleep more, so long sleepers in population studies are often already unwell.
How can poor sleep quality produce long nights? Show answer
People whose sleep is fragmented stay in bed longer to collect the same amount of sleep.
What is sleep efficiency and what level is healthy? Show answer
The share of time in bed spent asleep. Walker puts the healthy level at about 85 percent or higher.
Why does Walker think hypersomnia in depression was overstated? Show answer
Studies asked about time in bed, not time asleep. Depressed people stay in bed longer but their sleep is usually shorter and broken.
What does sleep timing have to do with depression? Show answer
A mismatch between a person's sleep schedule and body clock predicts it. Huberman feels low when the same hours fall later.
Do the experts say too much sleep is harmful in itself? Show answer
They do not know. Attia cites some emerging evidence, and Walker does not rule it out, comparing it to too much food or water.
How much sleep do most people need, according to Huberman? Show answer
At least six and ideally seven to eight hours. Children, teenagers and people under stress or physical strain need more.
What is Walker's rule after a bad night? Show answer
Do nothing. Do not sleep in, nap or go to bed early, because each undermines the next night's sleep.
When should long sleep be taken to a doctor? Show answer
When it is new or persistent, or comes with low mood or daytime exhaustion.