There are several reasons exercising before you go to bed can benefit your sleep. It can help you fall asleep faster or stay asleep longer, but it appears the timing of your exercise before bed has the most impact. Exercising too early before going to bed may make it harder to fall asleep. Choosing the sweet spot between too soon and not soon enough could be challenging, but researchers seem to have pinpointed a reasonable window of time, and that is four hours before going to bed.
There was research published in 2020, where they measured how moderate exercise timing affects sleep patterns. Although there were only sixteen participants in the study, they included both men and women between 22 and 24. The exercise performed for the study was running outdoors, either 4 or 2 hours before going to bed. The study results noted “improvements in sleep quality,” except “only when exercise was performed 4 h before habitual bedtime”.  This does show a positive correlation between exercising precisely 4 hours before going to bed and better sleep quality, suggesting this could be just what you need if you are having trouble sleeping, but remember, this study recommends “moderate” exercise.
A systematic review and analysis of research regarding the effects exercising in the evening have on sleep was published in 2019. The review concluded that exercising in the evening did not have any adverse effects on sleep. “However, sleep-onset latency, total sleep time, and sleep efficiency might be impaired after vigorous exercise ending ≤ 1 h before bedtime”. 
There are two main points to remember if you are interested in exercising before bed to get better quality sleep. The first is to try exercising right at 4 hours before your regular bedtime. This seems like the optimum time for the best sleep results. The second is to avoid vigorous exercise less than an hour before you go to bed. If you follow those two rules for exercising before bed, you should be all set for better sleep.
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- Saidi, O., et al. Effects of timing of moderate exercise in the evening on sleep and subsequent dietary intake in lean, young, healthy adults: randomized crossover study. European Journal of Applied Physiology. 2020. 120(7):1551-1562. https://pubmed.ncbi.nlm.nih.gov/32372217/ Times Cited 0 Journal Impact Factor 2.917
- Stutz, J., et al. Effects of Evening Exercise on Sleep in Healthy Participants: A Systematic Review and Meta-Analysis. Sports Medicine. 2019. 49(2):269-287. https://pubmed.ncbi.nlm.nih.gov/30374942/ Times Cited 9 Journal Impact Factor 9.759