Exercise does a great many things for the body and mind.
It boosts mood, increases productivity and creativity, burns calories, and helps you build muscle.
Exercise can also help reduce stress and improve your overall cardio metabolic health.
However, given all the benefits of exercise, there is some concern that exercising at the wrong time of day may impair your results and/or sleep quality.
So, when it comes to your workout's timing, does exercising at night affect the quality of your sleep?
Here's the breakdown of training time and sleep.
How Exercise Helps Sleep
Research shows that both acute and chronic exercise increases total sleep time and slow-wave sleep (SWS). <1>
Slow-wave sleep is the deepest of all of the sleep stages, meaning it is also possibly the most important stage of the sleep cycle. We do not dream during slow-wave sleep; however, during slow-wave sleep, the body does most of the work required to rest, grow, develop, and re-energize itself.
Basically, during slow-wave sleep, the body recovers from the day and recharges for the next day.
Exercise may also improve sleep quality in other ways because it reduces stress and burns calories, which depletes energy (ATP) stores, leading to increases in adenosine -- a neurotransmitter that causes feelings of fatigue and lethargy.
Exercise may also help reset the sleep-wake cycle by raising body temperature slightly, subsequently allowing it to drop and trigger sleepiness a few hours later.
The Right Timing
While there has been much speculation about whether or not exercising in the afternoon or evening may disrupt sleep, the good news is that we don't have to guess or postulate. Several studies have been carried out examining the effects of evening and nighttime exercise on healthy humans' sleep quality.
Up first, let's consider a 2019 meta-analysis titled Effects of Evening Exercise on Sleep in Healthy Participants: A Systematic Review and Meta-Analysis. <2>
Study #1
Researchers began with over 11,000 references and eliminated those studies that did not meet the extensive and diverse selection criteria. Ultimately the meta-analysis included 23 studies that examined the effects of evening exercise vs. a no-exercise control on various sleep metrics. <2>
For this meta-analysis, researchers defined "evening exercise" as any bout of exercise that occurred between 7.2 minutes to FOUR hours before bedtime, which is a fairly wide range.
The team of researchers discovered that individuals who performed evening workouts experienced significantly greater rapid eye movement (REM) and slow-wave ("deep") sleep while spending less time in stage 1 sleep, compared to individuals that did not exercise within 4 hours of bedtime. <2>
Other notable findings from the meta-analysis were that individuals who went to bed with a relatively higher body temperature were linked with poorer sleep efficiency.<2> Subjects were also more likely to wake after the onset of sleep. <2>
Study #2
Another study published in 2019 examined the effects of high-intensity exercise a few hours before bed on sleep quality. <3>
Each participant performed 30 minutes of high-intensity interval training (HIIT) alternating between 60 seconds of maximum effort and 240 seconds of 50% VO2 Max (active recovery) at one of the following times of day:
- Morning (6 a.m. to 7 a.m.)
- Afternoon (2 p.m. to 4 p.m.)
- Evening (7 p.m. to 9 p.m.)
Researchers observed no significant differences between the time of day the men exercised and its impact on the following sleep parameters <3>:
- Sleep Onset Latency (How Soon You Fall Asleep After Lying In Bed)
- Wake After Sleep Onset
- Sleep Efficiency
- Stage 1 Or Stage 2 Sleep
- Total Sleep Time
- Time In Bed
- Arousal Index
One fascinating finding from the study was that when the men exercised in the morning, they spent more time in stage 3 ("deep") sleep than before the trial started when they weren't exercising. This provides more evidence that exercise (regardless of the time of day) improves deep sleep.
Study #3
A 2020 study investigating the acute effects of evening exercise timing in healthy adults on their sleep quality found that evening exercise did not disrupt sleep. <4>
Participants in this study performed moderate-intensity workouts at different times, including 4 or 2 hours before bedtime. <4>
The Bottom Line on Sleep Quality and Evening Exercise
It has long been believed that intense exercise in the late evening may disrupt sleep.
However, the current body of evidence indicates that evening workouts do not impair sleep quality. Quite the opposite, they improve sleep quality and quantity.
There is some evidence indicating that high-intensity training within 60 minutes of bedtime may negatively impact sleep quality, but more research is needed to back up these early findings.
One other thing to consider is the individual.
While the research shows that exercising in the evening isn't likely to affect sleep quality, you also need to understand how it affects you personally. Research reports averages.
Only you know if exercising late in the day affects your sleep quality for better or worse.
If you find that evening workouts lead to better sleep, then get after it! On the flip side, if you find late workouts keep you up at night, then it'd be wise to shift your training to earlier in the day, if possible.
Regardless, remember that exercise (at any time of day) benefits sleep quality and quantity.
Ways To Improve Sleep Quality
There are a great many ways to improve sleep, including:
Be Consistent
Just like when you were a kid, having a set time to go to bed and wake up (even on the weekends) helps program your body to get in the right groove for sleep. It also helps establish a bedtime ritual -- a specific process that you go through each night, which helps reinforce your body and mind that it's time to go to sleep.
This could include showering, changing clothes, having a cup of herbal tea, reading, or any other calming activities that help you unwind and relax.
Limit Blue Light Exposure
Blue light disrupts melatonin production. Melatonin is the hormone in the body that regulates the sleep-wake cycle. Blue light is emitted from all sorts of electronics, including smartphones, laptops, TVs, tablets, and more.
Limit blue light exposure two hours before bed to avoid stimulating the brain and disrupting the body's process of winding down at night.
Keep Your Room Dark and Cool
Make sure your room is as dark as possible -- use blackout curtains and an eyeshade if needed. It also helps to keep your room on the cool side, between 60-67°F.
Get Comfy
Wear loose, comfortable clothing to bed, and make sure you have a comfortable mattress, pillow, and bedsheets. The last thing you need is to be tossing and turning because you're hot, uncomfortable, or itchy.
Be Smart with Food/Drink Choices
For better quality sleep, avoid nicotine, alcohol, and caffeine before bed.
Additionally, try not to eat a large meal within two hours or so of bedtime as many individuals find it difficult to sleep when feeling overly stuffed. If you want a little snack before bed, try having a protein shake or a bowl of protein yogurt with mixed berries. One of our favorite concoctions is 1 cup Greek Yogurt + 1 scoop Steel Whey™ Vanilla Milkshake, + 1 serving frozen berries.
Supplement When Needed
Even when you're doing everything right -- exercising during the day, limiting caffeine & alcohol, etc., can still be a challenge to unwind and shut off a hyperactive mind.
In times like this, it can help use natural sleep support and relaxation aid, such as Steel Dreams®.
Steel Dreams® is a natural, non-habit forming, sleep and recovery aid scientifically formulated to help reduce stress, calm a hyperactive mind, and improve sleep quality and duration. Even better, Steel Dreams® promotes relaxation and sedation without leaving you feeling groggy the next day!
References
- Driver HS, Taylor SR. Exercise and sleep. Sleep Med Rev. 2000 Aug;4(4):387-402. doi: 10.1053/smrv.2000.0110. PMID: 12531177.
- 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. https://doi.org/10.1007/s40279-018-1015-0
- Larsen, P. , Marino, F. , Melehan, K. , Guelfi, K. J., Duffield, R. and Skein, M. (2019), Evening high‐intensity interval exercise does not disrupt sleep or alter energy intake despite changes in acylated ghrelin in middle‐aged men. Exp Physiol. Accepted Author Manuscript. doi:10.1113/EP087455
- Saidi O, Davenne D, Lehorgne C, Duché P. Effects of timing of moderate exercise in the evening on sleep and subsequent dietary intake in lean, young, healthy adults: randomized crossover study. Eur J Appl Physiol. 2020 Jul;120(7):1551-1562. doi: 10.1007/s00421-020-04386-6. Epub 2020 May 5. PMID: 32372217.
