What the evidence shows
Regular aerobic exercise produces moderate, reliable improvements in sleep quality and sleep onset latency in adults, including people with insomnia. Benefits typically appear after several weeks rather than immediately, and they accumulate with consistency rather than intensity.
Resistance training also helps, though the evidence base is smaller. Mind-body forms — yoga, tai chi — have reasonable support, partly through the relaxation component.
Why it works
- Sleep pressure. Physical work builds the homeostatic drive to sleep.
- Lower baseline arousal. Regular exercisers show reduced sympathetic tone.
- Temperature. Exercise raises core temperature; the drop afterward mimics and amplifies the natural evening decline.
- Daylight, if you do it outside — the strongest circadian signal available.
- Mood and anxiety, both of which independently affect sleep.
Timing
- Morning and afternoon are best. Outdoor exercise in the morning does double duty: light plus activity.
- After about 4–6pm, vigorous exercise can be a problem for some people, because core temperature and arousal stay elevated for a couple of hours. Individual tolerance varies considerably — if late intense training does not affect you, do not change it.
- Gentle evening movement is fine and often helpful — walking, stretching, or slow Feldenkrais movement. See bedtime stretches.
The mistake active people make
People who train hard in the evening and sleep badly often assume training is the problem, when the more common issue is that they are in bed too long relative to how much they sleep, or that their arousal never comes down because the workday ended and the body did not stand down. If you train late and sleep well, nothing needs fixing.
If you cannot exercise much
Movement of any kind helps. For people with pain, limited mobility, or fatigue, the Feldenkrais approach is a reasonable entry point — it is done lying down, requires no strength or range, and the small-range principle means it does not raise arousal. See Feldenkrais for sleep and Feldenkrais for older adults.
A caution
Exercise is a useful addition and not a replacement for behavioural treatment of chronic insomnia. If you have had insomnia for months, add CBT-I rather than hoping more training will fix it.