We often hear about the importance of sleep for overall health as well as sleep for workout recovery. However, sleep recommendations for athletes are often discussed in the context of sleep guidelines for runners, cyclists, and other endurance athletes.
While endurance training requires more sleep than the average sleep recommendations for adults, it’s also critically important to get adequate sleep after strength training.
But, how much sleep to recover after training do you need?
Why is sleep important for weightlifters, whether competitive bodybuilders and powerlifters or everyday gym goers looking to get stronger, leaner, and more toned?
In this guide, we will discuss the role of sleep in the recovery from workouts, how much sleep to recover after training you need to optimize muscle building and workout recovery, and tips to improve sleep after strength training.
Let’s get started!
How Many Hours Of Sleep To Recover After Training Do You Need?
According to the American Academy of Sleep Medicine and Sleep Research Society, adults need a minimum of 7-9 hours of sleep per night.1Watson, N. F., Badr, M. S., Belenky, G., Bliwise, D. L., Buxton, O. M., Buysse, D., Dinges, D. F., Gangwisch, J., Grandner, M. A., Kushida, C., Malhotra, R. K., Martin, J. L., Patel, S. R., Quan, S., & Tasali, E. (2015). Recommended Amount of Sleep for a Healthy Adult: A Joint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society. Sleep, 38(6), 843–844. https://doi.org/10.5665/sleep.4716
You may need even more sleep per night if you are regularly engaging in high-intensity or high-volume strength training workouts.
However, there aren’t specific guidelines for how much sleep you need after strength training that will unilaterally apply to everyone.
Even within the normal 7 to 9 hours of recommended sleep per night for non-athletes, some people function perfectly fine on less sleep (closer to 7 hours), while others need closer to 9 hours of sleep per night to feel their best.
Aiming for 8-10 hours of sleep per night can be a good goal to facilitate recovery and support your strength training workouts.
Let’s look at why sleep is so important for supporting strength training workouts:
Is Working Out Affected By Sleep?
Although most studies that have looked at the effects of sleep deprivation have focused mostly on cognitive changes in military or emergency services personnel, there have been some studies looking specifically at the effects of sleep deprivation on exercise performance.
Many studies have looked at the impact of poor sleep on athletic performance, with almost all evidence suggesting that insufficient sleep decreases exercise performance in a variety of ways.
Unfortunately, most of the studies looking at the adverse effects of limited sleep on exercise performance have evaluated aerobic exercise such as running or cycling rather than resistance training workouts or power and strength athletic events.
For example, one study investigated how a poor night’s sleep would affect endurance running at 75% of the subjects’ VO2 max the next morning as well as time to exhaustion.2Mamiya, A., Morii, I., & Goto, K. (2021). Effects of partial sleep deprivation after prolonged exercise on metabolic responses and exercise performance on the following day. Physical Activity and Nutrition, 25(1), 1–6. https://doi.org/10.20463/pan.2021.0001
In addition to the sleep-deprived athletes having a shorter time to exhaustion, the researchers also found that the respiratory exchange ratio (RER) was significantly lower during the 20-minute VO2 testing run for the athletes who did not get enough sleep.
Respiratory exchange ratio is a metabolic metric that looks at the ratio between the expired carbon dioxide and the inhaled oxygen when you breathe.
When the RER is equal to 0.7, the body is burning entirely fat for fuel, whereas an RER of 1.0 indicates that carbohydrates are being burned for fuel.
Therefore, a lower RER (within the range of 0.7 and 1.0) is indicative of burning more fat for energy, while a higher RER means that you are using more carbohydrates.
The athletes who did not get enough sleep had a lower RER during the VO2 max workout than the athletes who got enough sleep.
They then tested themselves on the baseline condition when they had also gotten enough sleep; the researchers hypothesized that sleep deprivation increased energy expenditure, and thus depleted glycogen.
The researchers noted that sleep is necessary for your body to adequately replenish muscle glycogen.
While we tend to think that having adequate glycogen stores matters most for endurance exercise, replenishing muscle glycogen is equally important for high-intensity resistance training workouts.
When you are lifting heavy weights, the body is using blood sugar and relying on the ATP-PC system and glycolysis.
If you are not consuming carbs readily while you are doing your strength training workouts, muscle glycogen will be broken down to supply the glucose necessary to fuel your muscles for the high-force output.
However, if glycogen is scarce because you have burned through it by not getting enough sleep, your muscles will have to use more fat for fuel.
It takes quite a bit longer for ATP (energy) to be generated from oxidizing fat than it does when oxidizing carbohydrates, resulting in a lower force output and lower exercise tolerance for weightlifting workouts.
Additionally, researchers of a review of studies investigating the negative physiological effects of sleep-deprived workouts noted that poor sleep quality and inadequate sleep quantity cause an imbalance in the autonomic nervous system.3Hh, F., S, S., R, D., D, H., Aj, C., & T, M. (2015, February 1). Sleep and Athletic Performance: The Effects of Sleep Loss on Exercise Performance, and Physiological and Cognitive Responses to Exercise. Sports Medicine (Auckland, N.Z.). https://pubmed.ncbi.nlm.nih.gov/25315456/
This is the division of the nervous system that is under unconscious control and governs things like heart rate, blood pressure, respiratory rate, heart rate variability, and stress state.
The sympathetic nervous system and the parasympathetic nervous system are the two branches of the autonomic nervous system.
The sympathetic nervous system is associated with the “fight or flight response” and is activated in times of stress.
As such, activation of the sympathetic nervous system increases heart rate, blood pressure, respiration rate, etc.
The counterpart is the parasympathetic nervous system, which is often referred to as the “rest and digest nervous system” because it calms the body and is activated during rest and recovery.
These adverse nervous system changes that occur when you do not get enough sleep mimic the very same changes that are seen with overtraining syndrome, manifesting in symptoms in your strength training workouts like low energy, poor coordination, and increased levels of perceived exertion.
Sleep deprivation can also increase the production of pro-inflammatory cytokines and decrease the immune response.
These responses are also bad for resistance training because they will impede recovery after lifting weights.
What Are the Risks of Strength Training Without Sleeping Enough?
Given the effects of sleep deprivation on the body and brain, there are risks associated with strength training without getting enough sleep.
The biggest concern is the potential increase in the risk of injury or illness.
In an acute sense, strength training without getting enough sleep can increase the risk of injury because sleep deprivation impairs coordination, reaction time, concentration, and judgment.
You are more apt to drop weights, use poor technique, be unable to properly brace your core, make bad decisions in the weights or reps that you do, etc. if you are not thinking clearly or are tired from not sleeping enough before working out.
Failing to get enough sleep to recover after training on a chronic basis can also increase the risk of injury and illness because sleep deprivation acts as a significant stressor to the body.
This can cause your cortisol levels to increase along with other markers of systemic inflammation, which can compromise immune function.
Furthermore, because sleep is critical for recovering properly after a workout, when you lift weights and then do not get enough sleep, some of your gains in the gym might be compromised.
Particularly if you are burning through glycogen by being awake more of the night than normal—as elucidated in the study referenced above—muscle protein synthesis will be impaired.4Petit, J.-M., Burlet-Godinot, S., Magistretti, P. J., & Allaman, I. (2014). Glycogen metabolism and the homeostatic regulation of sleep. Metabolic Brain Disease, 30(1), 263–279. https://doi.org/10.1007/s11011-014-9629-x
Muscle protein synthesis is the process by which muscles are repaired and strengthened after lifting weights.
Although we tend to think about the importance of eating enough protein for muscle recovery and muscle building from strength training, you also need carbohydrates (glucose/glycogen) for the process of muscle protein synthesis to take place.
If you aren’t getting enough sleep and your body is using glycogen to fuel your cells while you are awake, this resource cannot go towards repairing the muscle damage you incurred in your workout.
Not only will this limit the gains in muscle growth from strength training, but it will also impede the muscle recovery process, setting you up for an increased risk of injury and overtraining if you lift weights again the next day and inadequate sleep is a chronic problem in your life.5Saner, N. J., Lee, M. J. ‐C., Pitchford, N. W., Kuang, J., Roach, G. D., Garnham, A., Stokes, T., Phillips, S. M., Bishop, D. J., & Bartlett, J. D. (2020). The effect of sleep restriction, with or without high‐intensity interval exercise, on myofibrillar protein synthesis in healthy young men. The Journal of Physiology, 598(8), 1523–1536. https://doi.org/10.1113/jp278828
Perhaps most importantly, the body releases human growth hormone (HGH) when you sleep.
Human growth hormone plays a critical role in muscle repair and growth because HGH stimulates the muscle protein synthesis process.
Evidence suggests that low levels of HGH can cause a loss of muscle mass and compromised strength and exercise capacity.6Validate User. (n.d.). Academic.oup.com. https://academic.oup.com/jcem/article/83/2/382/2865179
Studies have found that the more deep sleep you get, the more HGH your body produces, while a lack of deep sleep decreases HGH secretion.7Van Cauter, E. (2000). Age-Related Changes in Slow Wave Sleep and REM Sleep and Relationship With Growth Hormone and Cortisol Levels in Healthy Men. JAMA, 284(7), 861. https://doi.org/10.1001/jama.284.7.861
Testosterone and other anabolic hormones responsible for muscle repair and muscle growth are also released more during deep sleep.
Again, aiming for 8-10 hours of sleep per night after working out can be a good insurance policy to give your body time to recover and repair after strength training, and to set you up for success for the next workout.
If you find that you are sleeping many hours at night after weightlifting, check out our guide to the risks of oversleeping here.
