Exercising is crucial for overall health, but when you hit the gym can significantly affect how well you sleep. A recent review of 15 studies involving 194 healthy adults, published in Sleep Medicine Reviews, sheds light on this connection. Researchers at Concordia University found that working out too close to bedtime disrupts sleep, while exercising earlier in the evening may actually improve it.
The Two-Hour Rule
The study confirms that high-intensity exercise within two hours of bedtime leads to longer sleep latency (difficulty falling asleep) and reduced sleep duration. The physiological response—elevated heart rate and body temperature—makes it harder for the body to wind down. This is why vigorous activity right before bed can leave you tossing and turning.
However, the research also reveals a surprising benefit: exercising two to four hours before bed can promote better sleep. Participants in these studies experienced faster sleep onset and increased total sleep time. The catch? They spent less time in REM sleep, the stage associated with dreaming.
Who Benefits Most?
The ideal timing isn’t universal. Sedentary individuals appear to benefit most from evening workouts, as physical activity can help regulate their sleep cycles. Additionally, night owls may find evening exercise more advantageous than early birds. The best exercise for sleep in these studies was cycling.
Why It Works (and Doesn’t)
The positive effects of evening exercise are likely due to fatigue and the release of endorphins, which can promote relaxation. However, the body needs time to recover. Allowing at least two hours for cooldown is vital to lower heart rate and body temperature before attempting sleep.
The Bottom Line
Timing matters. While exercising at any point in the day supports health, prioritizing workouts two to four hours before bed appears to be the sweet spot for many people’s sleep. If you’re struggling with insomnia, consider adjusting your exercise schedule or opting for a lighter routine closer to bedtime.
