The short answer
- The 2021 expert consensus on athlete sleep concluded that a one-size-fits-all recommendation, including the familiar seven to nine hours, is unlikely to be ideal.
- Going a full night without sleep does reduce performance. What one to three shortened nights does, which is the situation you actually face, is still unclear.
- Habitually sleeping under seven hours raises susceptibility to respiratory infection in the general population. That is the finding most relevant to a training block.
- The research has real problems: weak experimental control, few female participants, and questions about the tools used to measure sleep.
- What to do about it is boring and works. Regular wake time, less screen time late, and arranging training so it does not eat your nights.
Sleep advice for runners has a confidence problem. The numbers get quoted with a precision the research does not have, usually by people selling something adjacent to a mattress.
The panel that reviewed all of it reached a more modest conclusion.
What the consensus actually says
Read that carefully, because it is more interesting than the usual summary of it.
A full night with no sleep hurts your running. Fine, nobody doubted that. But the thing that actually happens to you, a few short nights in a row during a busy week, has not been pinned down. And the panel specifically declined to hand out a target number.
They also said out loud that the literature has few women in it, which is a problem that runs through most of sports science and rarely gets mentioned in the popular version.
The finding that matters most
Buried in the same review is the bit I think runners should care about more than performance.
Habitually sleeping under seven hours a night increases susceptibility to respiratory infection. That comes from studies in the wider population rather than in athletes specifically, and the authors are clear about it1.
Think about what that means across a marathon block. Not a slightly worse tempo run. A week off with a chest cold in the middle of your build, which costs far more than a slow session ever would. Every runner I have worked with who trains hard on five hours a night eventually loses a fortnight to illness, and they almost never connect the two.
Why training makes sleep worse
Running does not automatically improve your sleep, and hard running can make it worse.
An evening interval session raises core temperature and arousal at the exact time you want both falling. A 5am alarm to fit a run in before work removes sleep from the end you cannot get back. Race anxiety, travel to events, unfamiliar beds. The consensus lists sport-specific factors covering training, travel and competition, alongside non-sport factors including stress and anxiety1.
Those are the things to fix, and most of them are scheduling rather than sleep hygiene.
The things that work
Regular wake time, seven days a week, including weekends. This matters more than bedtime, because your body clock anchors to when light hits your eyes rather than when you switched the lamp off.
Wind down properly. Not as a wellness ritual, just enough gap between the last stimulating thing and the pillow that your nervous system has somewhere to land.
Cool, dark, quiet. Earplugs and an eye mask are cheap and unglamorous and work.
Caffeine has a long tail. Half of an afternoon coffee is still circulating at bedtime for most people, and runners drink a lot of coffee.
A short nap, twenty to thirty minutes, is useful if your nights are genuinely restricted. The consensus notes that research into napping and sleep banking is still needed, so treat it as a reasonable thing to try rather than a proven strategy1.
When poor sleep is a symptom
Sometimes sleep is the thing that broke. Sometimes it is telling you something else broke first.
Sleep disturbance shows up as a feature of under-fuelling, where it sits alongside low mood, feeling cold, and recovery that stopped working2. It is also one of the factors the postpartum return-to-running consensus lists as a reason to modify a training plan rather than push through it3.
If your sleep got worse at the same time as your training got heavier and your appetite changed, sleep hygiene is not the answer to that. Our article on under-fuelling covers what is.
When to get it looked at
Daytime exhaustion despite adequate time in bed is the one people put up with longest. It is worth investigating rather than working around.