How Sleep Deprivation Affects Muscle Growth and Recovery: What the Research Shows

Training is a balance between stress and recovery. Muscles break down with training and rebuild (stronger) during recovery. While we often focus on the training part, we may forget that recovery deserves the same emphasis, and that sleep is a critical part of recovery. In today’s article, we’ll explore the evidence-based relationship between sleep and muscle growth and how sleep deprivation can hinder of muscle recovery. Let’s look at:

• The consequences of poor sleep
• The sleep and muscle protein synthesis relationship
• The connection between sleep and testosterone and cortisol levels (and what it means for muscles)
• Sleep quantity vs. quality – why both matter
• Sleep supplements and the benefits of melatonin, L-theanine, and saffron extract
• How to optimize your sleep
• FAQs

What Happens to Your Body When You Do Not Get Enough Sleep?

Not getting enough sleep affects physical and mental health. Just think about a time when you slept poorly and how you felt the next day. You might have been tired, foggy, hungry, or irritable, which goes to show how critical sleep is for a well-functioning body and mind. While a single night of poor sleep can significantly affect in how your body functions, increasing the risk of driving accidents or loss of work productivity, chronic sleep deprivation compounds these effects. (1) Lack of sleep can impair or affect:

• Cognitive performance
• Memory formation
• Mood
• Glucose metabolism
• Appetite regulation and food intake
• Immune function
• Removal of cellular waste
• Hormone levels
• Fitness level
• Body composition and lean body mass (1)

Sleep and Muscle Protein Synthesis: Why Growth Happens When You Rest, Not When You Train

Exercise stresses and damages muscle, but it’s during rest and recovery (including sleep) that the body repairs and strengthens via muscle protein synthesis. From this perspective, a recovery period that includes adequate sleep is necessary for muscle gains. Sleep is essential for post-exercise recovery. First, while training produces muscle fatigue, sleep helps reverse it, allowing the muscles to recover from the strain of exercise. (2) Second, sleep promotes the environment necessary for muscle repair and recovery while sleep deprivation may impair protein synthesis. We see this in the research in a few ways:

• Sleep impacts the rate of muscle repair after training (2)
• Sleep accelerates recovery after a muscle injury (3)
• Sleep loss or restriction is associated with muscle loss (4)

How Sleep Deprivation Lowers Testosterone and Raises Cortisol

Sleep has a restorative effect on the endocrine system, and poor sleep disrupts hormone balance. (2)

Let’s look at testosterone and cortisol.

Healthy testosterone levels support muscle growth and strength. On one hand, low testosterone may affect sleep quality. And on the other hand, poor sleep can lower testosterone levels. (5)

The research shows a correlation between poor sleep and testosterone levels. In one study, impaired sleep correlated with lower testosterone levels in men, as did advanced age and higher weight. (6)

Another study suggests that the correlation between sleep and testosterone is U-shaped in older men, with the highest testosterone levels associated with 9.9 hours of sleep. Both longer and shorter sleep durationswere associated with lower testosterone. This study also examined many other sleep parameters. Prolonged sleep latency (the time it takes to fall asleep) was associated with lower muscle mass. Insomnia was associated with slower walking speed and weaker grip strength. While this isn’t the optimal study design and doesn’t prove causation, the associations are interesting. (7)

A systematic review and meta-analysis of 18 studies looked at the effect of sleep deprivation on testosterone levels. This study demonstrated that 24 hours or more of sleep deprivation reduced serum testosterone levels, whereas partial deprivation did not. Nonetheless, it appears that sleep is important for maintaining testosterone levels in men. (8)

Cortisol is an adrenal hormone that plays an important role in the body’s circadian rhythm, or sleep-wake cycle. In a normal pattern, cortisol rises upon waking in the morning and then declines throughout the afternoon and evening to promote sleep. A disrupted pattern or high cortisol levels can impair sleep. A systematic review and meta-analysis of 24 studies suggests that those with poor or restricted sleep may have higher cortisol levels than those with regular sleep patterns when cortisol is measured multiple times throughout the day. (9)

Another study suggests that sleep restriction tends to increase late-afternoon and early-evening cortisol levels, but not overall cortisol levels. However, the shift in the cortisol pattern is significant: higher cortisol later in the day after poor sleep can set you up for another night of poor sleep. (10)

The bottom line is that poor sleep may disrupt hormonal patterns involved in recovery, which can contribute to a less favorable environment for muscle repair, adaptation, and performance. This doesn’t mean you have to obsess over hormones, just focus on the behaviors you can control, as much of the time you can.(11)

Sleep Quality Vs. Sleep Duration: What Matters Most for Recovery and Performance

Both quality and duration matter for recovery and training adaptation. Additionally, sleep timing that’s aligned with the natural circadian rhythm is preferred to optimize sleep benefits. (2)

The typical sleep recommendations are 7-9 hours for adults and 7-8 hours for older adults. However, research suggests that elite athletes may require more sleep than non-athletes. Inadequate sleep duration is typically defined as less than 7 hours per night. (1,2)

Getting enough sleep is only part of the equation. Sleep quality also matters. Sleep stages include REM (rapid eye movement) and non-REM states. Non-REM is further divided into light sleep (stages 1 and 2) and deep sleep (stage 3). Deep sleep is required for physical recovery; it’s when growth hormone increases. (2)

Indicators of good sleep quality include:

• Falling asleep easily
• Sleeping through the night
• Ability to quickly fall back asleep during awakenings
• Good sleep architecture – spending adequate time in each sleep stage during each sleep cycle
• No daytime sleepiness or dysfunction (2)

While all these pieces are important, there isn’t a one-size-fits-all sleep prescription. Depending on your training, you may need more sleep and recovery support.

Melatonin, L-Theanine, and Saffron: Evidence-Based Ingredients that Support Better Sleep

Supplements for sleepare essentially muscle-recovery supplements because sleep is a key part of exercise recovery, supplements that meaningfully improve sleep may indirectly support recovery.

Let’s look at some of the evidence-based ingredients that support sleep duration, quality, and timing. 

Melatonin for Sleep

Melatonin, the sleep hormone, works in opposition to cortisol, rising in the evening and night to promote sleep, with low levels during the day. In addition to its role in regulating the circadian rhythm, melatonin benefitsinclude immune support, antioxidant activity, and anti-inflammatory signaling. (12)

How does melatonin work? Melatonin supplementation works by signaling the body that it’s time for sleep and supporting the circadian rhythm. Research suggests that melatonin supplementation can improve sleep quality, reduce the time it takes to fall asleep, and extend sleep duration. (13, 14)

When it comes to the melatonin dosage, more isn’t necessarily better. In fact, you’ll get the best results from the lowest effective dose. Instead of 5 or 10 milligrams, which you’ll commonly find over-the-counter, start with 1 or 2 mg.

L-Theanine for Sleep

L-theanine is a naturally occurring, non-protein amino acid found in tea, with particularly high levels in green tea. It’s another helpful supplement to consider for sleep support.

What does L-theanine do? L-theanine promotes calming effects on the nervous system, can reduce stress and anxiety, and counter sleep disruption caused by caffeine. L-theanine benefits for sleep include improved sleep latency, sleep satisfaction, and feeling refreshed in the morning with an L-theanine dosage starting at 200 mg. (15)

Saffron Extract Supplement for Sleep Saffron is a spice and medical herb from crocus flowers that emerging research shows supports sleep. Saffron benefits include improved sleep quality and duration, as well as improved mood. (16, 17)

Affron, a concentrated, standardized saffron extract, is the primary form of saffron studied in clinical trials. An effective dose is in the range of 25 to 30 mg per night.

How to Optimize Your Sleep for Training Recovery: What the Research Recommends

Optimizing your sleep supports training results and recovery. Yet, getting enough, high-quality sleep can be challenging given stress, technology, productivity goals, and other factors. Here are some tips for optimizing sleep.

1. The good news is that while sleep is needed for exercise recovery, exercise also promotes better sleep. And both are good for overall health. (1)
2. Adopt good sleep hygiene. Your daily habits and bedtime routine can help (or hinder) nighttime sleep. Blue light exposure during the day,while blocking it at night, is helpful for supporting the circadian rhythm. Also, limit screen time and stressful media before bed, while establishing a relaxing evening routine.
3. Choose supplements for muscle recovery. Outwork Nutrition Recovery is an evidence-based formula to support muscle growth and strength.
4. Take the best sleep supplement. Outwork Nutrition Sleep Aid combines 2 mg of melatonin, 200 mg of L-theanine, and 28 mg of Affron in a single 2-capsule formula. You can start with 1 capsule for personalized dosing.

One of the best supplements for muscle recoveryis actually a sleep formula. Time and time again, research demonstrates the importance of sleep to optimize muscle recovery and training goals. Let Outwork Nutrition Sleep Aid help!

FAQs

How does poor sleep affect muscle growth and recovery?

Muscle growth and recovery occur during rest and sleep, not during training itself, and are a necessary component to reach training goals. Inadequate sleep may hinder growth and recovery.

How many hours of sleep do athletes need for optimal performance?

Adults typically need 7 to 9 hours of sleep, but elite athletes may need more than their non-athlete counterparts. Your optimal amount of sleep is individual to you.

Can sleep deprivation lower testosterone levels?

Yes. Research demonstrates that sleep deprivation correlates with lower testosterone production.

Does melatonin actually improve sleep quality for athletes?

Melatonin can improve certain sleep outcomes, especially sleep onset and circadian timing, though responses vary by person, dose, timing, and sleep issue.

What supplements are most effective for supporting better sleep?

The most effective sleep-support supplements include low-dose melatonin, L-theanine, and saffron extract (Affron).  

References

1. Dolezal BA, Neufeld EV, Boland DM, Martin JL, Cooper CB. Interrelationship between Sleep and Exercise: A Systematic Review. Adv Prev Med. 2017;2017:1364387. doi: 10.1155/2017/1364387. Epub 2017 Mar 26. Erratum in: Adv Prev Med. 2017;2017:5979510. doi: 10.1155/2017/5979510. PMID: 28458924; PMCID: PMC5385214.
2. Doherty R, Madigan SM, Nevill A, Warrington G, Ellis JG. The Sleep and Recovery Practices of Athletes. Nutrients. 2021 Apr 17;13(4):1330. doi: 10.3390/nu13041330. PMID: 33920560; PMCID: PMC8072992.
3. Chennaoui M, Vanneau T, Trignol A, Arnal P, Gomez-Merino D, Baudot C, Perez J, Pochettino S, Eirale C, Chalabi H. How does sleep help recovery from exercise-induced muscle injuries? J Sci Med Sport. 2021 Oct;24(10):982-987. doi: 10.1016/j.jsams.2021.05.007. Epub 2021 May 18. PMID: 34074604.
4. Saner NJ, Lee MJ, Pitchford NW, Kuang J, Roach GD, Garnham A, Stokes T, Phillips SM, Bishop DJ, Bartlett JD. The effect of sleep restriction, with or without high-intensity interval exercise, on myofibrillar protein synthesis in healthy young men. J Physiol. 2020 Apr;598(8):1523-1536. doi: 10.1113/JP278828. Epub 2020 Mar 11. PMID: 32078168; PMCID: PMC7217042.
5. Wittert G. The relationship between sleep disorders and testosterone in men. Asian J Androl. 2014 Mar-Apr;16(2):262-5. doi: 10.4103/1008-682X.122586. PMID: 24435056; PMCID: PMC3955336.
6. Patel P, Shiff B, Kohn TP, Ramasamy R. Impaired sleep is associated with low testosterone in US adult males: results from the National Health and Nutrition Examination Survey. World J Urol. 2019 Jul;37(7):1449-1453. doi: 10.1007/s00345-018-2485-2. Epub 2018 Sep 17. PMID: 30225799.
7. Auyeung TW, Kwok T, Leung J, Lee JS, Ohlsson C, Vandenput L, Wing YK, Woo J. Sleep Duration and Disturbances Were Associated With Testosterone Level, Muscle Mass, and Muscle Strength--A Cross-Sectional Study in 1274 Older Men. J Am Med Dir Assoc. 2015 Jul 1;16(7):630.e1-6. doi: 10.1016/j.jamda.2015.04.006. Epub 2015 May 8. PMID: 25959075.
8. Su L, Zhang SZ, Zhu J, Wu J, Jiao YZ. Effect of partial and total sleep deprivation on serum testosterone in healthy males: a systematic review and meta-analysis. Sleep Med. 2021 Dec;88:267-273. doi: 10.1016/j.sleep.2021.10.031. Epub 2021 Nov 8. PMID: 34801825.
9. Chen Y, Xu W, Chen Y, Gong J, Wu Y, Chen S, He Y, Yu H, Xie L. The effect of acute sleep deprivation on cortisol level: a systematic review and meta-analysis. Endocr J. 2024 Aug 8;71(8):753-765. doi: 10.1507/endocrj.EJ23-0714. Epub 2024 May 21. PMID: 38777757.
10. O'Byrne NA, Yuen F, Butt WZ, Liu PY. Sleep and Circadian Regulation of Cortisol: A Short Review. CurrOpinEndocrMetab Res. 2021 Jun;18:178-186. doi: 10.1016/j.coemr.2021.03.011. Epub 2021 May 5. PMID: 35128146; PMCID: PMC8813037.
11. Dattilo M, Antunes HK, Medeiros A, Mônico Neto M, Souza HS, Tufik S, de Mello MT. Sleep and muscle recovery: endocrinological and molecular basis for a new and promising hypothesis. Med Hypotheses. 2011 Aug;77(2):220-2. doi: 10.1016/j.mehy.2011.04.017. Epub 2011 May 7. PMID: 21550729.
12. Minari TP, Pisani LP. Melatonin supplementation: new insights into health and disease. Sleep Breath. 2025 Apr 25;29(2):169. doi: 10.1007/s11325-025-03331-1. PMID: 40278958.
13. Fatemeh G, Sajjad M, Niloufar R, Neda S, Leila S, Khadijeh M. Effect of melatonin supplementation on sleep quality: a systematic review and meta-analysis of randomized controlled trials. J Neurol. 2022 Jan;269(1):205-216. doi: 10.1007/s00415-020-10381-w. Epub 2021 Jan 8. PMID: 33417003.
14. Cruz-Sanabria F, Bruno S, Crippa A, Frumento P, Scarselli M, Skene DJ, Faraguna U. Optimizing the Time and Dose of Melatonin as a Sleep-Promoting Drug: A Systematic Review of Randomized Controlled Trials and Dose-Response Meta-Analysis. J Pineal Res. 2024 Aug;76(5):e12985. doi: 10.1111/jpi.12985. PMID: 38888087.
15. Cotter J, Caddick CE, Harper JL, Ebajemito JK. Examining the effect of L-theanine on sleep: a systematic review of dietary supplementation trials. NutrNeurosci. 2026 Feb;29(2):224-238. doi: 10.1080/1028415X.2025.2556925. Epub 2025 Nov 1. PMID: 41176609.
16. Sadat Rafiei SK, Abolghasemi S, Frashidi M, Ebrahimi S, Gharei F, Razmkhah Z, Tavousi N, Mahmoudvand B, Faani M, Karimi N, Abdi A, Soleimanzadeh M, AhmadpourYoushanlui M, Sadatmadani SF, Alikhani R, Pishkari Y, Deravi N. Saffron and Sleep Quality: A Systematic Review of Randomized Controlled Trials. NutrMetab Insights. 2023 Jul 18;16:11786388231160317. doi: 10.1177/11786388231160317. PMID: 37484523; PMCID: PMC10357048.
17. Lopresti AL, Smith SJ, Marx W, Díez-Municio M, Morán-Valero MI. An Examination into the Effects of a Saffron Extract (Affron) on Mood and General Wellbeing in Adults Experiencing Low Mood: A Randomized, Double-Blind, Placebo-Controlled Trial. J Nutr. 2025 Jul;155(7):2300-2311. doi: 10.1016/j.tjnut.2025.05.024. Epub 2025 May 23. PMID: 40414301.