Aim for sufficient sleep duration
Give yourself a realistic time-in-bed window most adults need, instead of running a deficit.
Why it works
Most adults need roughly 7–9 hours of sleep, and chronic short sleep accumulates as a deficit that degrades attention, mood, and metabolic regulation. Because people habituate to feeling tired, self-rated alertness is an unreliable gauge — you can be impaired without feeling it.
How to do it
- Back-calculate a bedtime from your fixed wake time and a realistic sleep need.
- Schedule enough time-in-bed (slightly more than your target sleep) as a non-negotiable block.
- Judge sufficiency by daytime function over weeks, not by one night.
Evidence
Consensus guidelines recommend ~7+ hours for adults, and experimental sleep restriction reliably impairs cognition and mood. The general "need" range is well supported. (rct)
Why We Sleep’s strongest mortality and "shorter sleep = shorter life" framing has been criticized as overstated; the safe claim is that chronic short sleep impairs function, not that any specific hour count is destiny.
Sources
- Watson et al. (2015), AASM/SRS consensus on recommended sleep duration, SLEEP
Common mistake
Believing you’re "fine on 5 hours" because you no longer feel tired — habituated sleepiness hides real performance decline.
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More practices for Why We Sleep, Translated Into Practice
- Work with sleep pressure (the adenosine clock)
Let adenosine build across the day instead of papering over it with caffeine and naps.
- Keep the circadian clock on time
Use stable timing and light so your internal clock and your sleep window agree.
- Protect your REM sleep
Guard the back half of the night, when most REM and emotional processing happen.
- Value deep NREM (slow-wave) sleep
Front-load and protect deep sleep, the most physically restorative stage.
- Separate the science from the overstatement
Keep the reliable sleep practices; hold the scariest popular claims loosely.