How much sleep do you need when you exercise?

Seven, eight or nine hours: which number is right?

Between seven and nine hours a night. That is the range the NHS and the US National Institutes of Health give for adults, with seven hours as the floor. Neither publishes a separate scale for women who run, dance or play basketball twice a week, so the benchmark stays the same when you take up sport.

The nuance lies elsewhere. According to the US institute that covers heart, lung and sleep health, sleeping more than nine hours is not necessarily harmful and may help young adults and people catching up after a run of short nights. If you have just started training again and your body asks for an extra hour, give it that hour without judging yourself.

How do I know if I’m getting enough?

Look at your days, not your alarm clock. If you are constantly tired during the day, you probably do not get enough sleep, the NHS says. Three other signs point to poor-quality sleep: you take a long time to drop off, you wake several times a night, or you get up unrefreshed even though the hours were there.

The shortfall shows in training too. While you sleep, your body works to maintain its physical health and your brain stores what it learned during the day. Short sleep makes it harder to focus and think clearly. On a pitch or in a group class, that might mean a movement that will not stick, an instruction you forget, a session you get through instead of enjoying.

Will an evening workout keep me awake?

Not necessarily, and regular exercise is one of the habits that improve sleep, according to both US and UK health authorities. For many women the only free slot comes after work, the commute and the children’s dinner. A session at that hour beats no session at all.

The caution applies if you already sleep badly. In that case the NHS advises against exercising in the four hours before bed, against tea or coffee in the six hours before, and in favour of getting up at the same time every day. The US Centers for Disease Control and Prevention adds two more: switch off screens at least 30 minutes before bedtime and keep the bedroom quiet and cool, as far as the season allows.

My nights are too short: is a nap enough?

It helps, but it does not replace the night. When night-time sleep falls short, a nap improves alertness and performance, according to Inserm, France’s national medical research institute. Keep it short: 15 to 20 minutes, early in the afternoon, somewhere quiet. Length and timing matter, so that the nap does not make it harder to fall asleep in the evening.

A baby who wakes, a night shift, late evenings during Ramadan: some periods shorten your nights without asking. In those weeks, keep a steady wake-up time and allow yourself that short nap. One caveat: if you have insomnia, the NHS advises against napping during the day.