In today’s fast-paced world, many people squeeze in workouts wherever they can often late at night, after work or family duties. While exercising is a cornerstone of good health, science suggests that the timing of your workout may play a significant role in the quality of your sleep. In fact, working out too close to bedtime might be doing more harm than good when it comes to falling and staying asleep.
Exercise is known to increase core body temperature, heart rate, and the release of stimulating hormones like adrenaline and cortisol. These are excellent effects during the day, helping you feel energized and alert. However, at night, your body is preparing for the opposite. In order to transition into restful sleep, your core temperature needs to drop, your heart rate needs to slow, and your body should enter a parasympathetic state often referred to as "rest and digest."
A 2019 meta-analysis published in Sports Medicine found that vigorous exercise performed less than an hour before bedtime significantly worsened sleep quality. The researchers concluded that intense nighttime workouts can delay the onset of sleep and reduce total sleep time, especially in individuals who already experience trouble falling asleep. The body may remain too physiologically aroused to settle into restful slumber.
Additionally, the National Sleep Foundation explains that the body’s natural circadian rhythm a biological clock that regulates sleep-wake cycles is sensitive to timing cues, including activity and light. High-intensity exercise in the late evening can act as a signal that it’s still daytime, delaying melatonin production and interfering with the natural wind-down process.
Cortisol, often referred to as the "stress hormone," is released in response to physical exertion. A 2005 study in the Journal of Endocrinological Investigation found that evening workouts led to increased cortisol levels at night, which could impair sleep onset and reduce time spent in deep sleep stages those critical for physical recovery and memory consolidation.
However, not all nighttime workouts are problematic. Low-intensity activities such as yoga, stretching, or light walking have been shown to support relaxation and improve sleep quality. These forms of movement may enhance parasympathetic nervous system activity, lowering heart rate and promoting calmness before bed.
For those who can only work out in the evening, the solution might be moderation and timing. Experts generally recommend finishing moderate-to-intense exercise at least 90 minutes before bedtime to allow the body to cool down and the nervous system to settle. You can also help your body transition into sleep mode with a post-exercise wind-down routine that includes stretching, dim lighting, and screen-free time.
Understanding how your individual body responds to evening workouts is key. While some people may not notice any sleep disturbances, others may find their sleep significantly disrupted. If you're experiencing trouble falling asleep or waking up frequently during the night, your late-night gym sessions could be a factor worth adjusting.
Sources:
Kredlow, M. A., Capozzoli, M. C., Hearon, B. A., Calkins, A. W., & Otto, M. W. (2015). The effects of physical activity on sleep: a meta-analytic review. Journal of Behavioral Medicine, 38(3), 427–449.
Stutz, J., Eiholzer, R., & Spengler, C. M. (2019). Effects of Evening Exercise on Sleep in Healthy Participants: A Systematic Review and Meta-Analysis. Sports Medicine, 49(2), 269–287.
National Sleep Foundation – Exercise and Sleep
Leproult, R., & Van Cauter, E. (2010). Role of sleep and sleep loss in hormonal release and metabolism. Endocrine Development, 17, 11–21.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Individual sleep and exercise responses can vary. Please consult your doctor or a qualified health professional before making significant changes to your fitness or sleep routine.