In 30 seconds
- Adults need 7 hours or more. Many athletes sleep less than 7, with frequent awakenings.
- Sleeping more improves performance: basketball players who slept almost 2 hours more ran faster and were 9% more accurate.
- Caffeine 6 hours before going to bed can take away more than an hour of sleep without you noticing.
- Training in the evening does not worsen sleep, except for a hard effort that ends less than an hour before going to bed.
You train, you eat well and yet you are not making progress. Often the missing piece is what happens when you are not training: sleep. This guide summarises what the studies say and what you can change from tonight.
Hours of sleep
How much to sleep each night
How much to sleep
The American Academy of Sleep Medicine recommends 7 hours or more a night for adults, and considers 6 or fewer not enough to maintain health 1. The National Sleep Foundation gives these ranges 2:
| Age | Recommended |
|---|---|
| 18-25 years | 7-9 hours |
| 26-64 years | 7-9 hours |
| 65 or over | 7-8 hours |
Source: National Sleep Foundation, 2015. The American Academy of Sleep Medicine recommends 7 hours or more for adults.
In athletes, the 2021 expert consensus notes that many habitually sleep less than 7 hours, with frequent awakenings, and recommends tailoring the target to each person rather than using a single figure 3.
Sleeping more, sleeping less
What was measured with more (or less) sleep
Why it matters if you train
You perform better
In a Stanford study, 11 basketball players went from sleeping less than 7 hours to almost 8.5, extending their time in bed for 5-7 weeks. Their sprint time fell from 16.2 to 15.5 seconds, they were 9% more accurate in free throws and three-pointers, and they felt better physically and mentally 4.
You lose fat more effectively
In a trial on the same diet for two weeks, those who slept 5.5 hours instead of 8.5 lost less than half as much fat (0.6 kg compared with 1.4 kg) and more lean mass, and they were hungrier 5.
You look after your health
In the general population, habitually sleeping too little is associated with a higher risk of respiratory infections 3.
Caffeine, the great overlooked factor
In one study, 400 mg of caffeine taken 6 hours before going to bed took away more than an hour of measured sleep. The striking part: the participants did not notice 6. EFSA notes that doses of about 100 mg can affect some people's sleep if taken close to bedtime 7.
| Drink | Caffeine |
|---|---|
| Filter coffee (200 ml) | 90 mg |
| Espresso (60 ml) | 80 mg |
| Can of energy drink (250 ml) | 80 mg |
| Tea (220 ml) | 50 mg |
| Can of cola (355 ml) | 40 mg |
Source: EFSA, 2015, as reported by EUFIC. Values vary with preparation.
If you train in the afternoon, watch out for pre-workouts containing caffeine.
What if I train in the evening?
Good news: a meta-analysis of 23 studies did not find that evening exercise worsened sleep in healthy people. The only exception was intense exercise that ends less than an hour before going to bed 8. If that is you, leave time for your heart rate to come down before you get into bed.
Habits
The basic sleep habits
Habits that help
The expert consensus proposes a sleep “toolbox” that starts with education and screening for sleep problems 3. These are the basic habits:
- Regular times: go to bed and get up at similar times, including at weekends.
- Light: natural light in the morning and dim light in the evening. Screens kept out of bed.
- Bedroom: dark, quiet and cool.
- Caffeine: none from mid-afternoon onwards.
- Alcohol and heavy dinners: best kept well away from bedtime.
- Travel and competitions: these are risky times for sleep; plan for them.
If you still sleep badly on an ongoing basis, check with your doctor: there may be a sleep disorder behind it.
What about supplements?
They complement your habits. The most studied ingredients for the night are glycine, L-theanine and tryptophan, magnesium and melatonin, and each one acts through a different pathway. We go through them one by one in sleep supplements if you train.
Frequently asked questions
How many hours of sleep do you need if you exercise?
Adults need 7 hours or more, and the usual reference is 7 to 9. The expert consensus on athletes recommends tailoring the target to each person, according to how they feel and perform.
Does lack of sleep affect fat loss?
Yes. In a trial on the same diet, those who slept 5.5 hours instead of 8.5 lost less than half as much fat and more lean mass, and they were hungrier.
What time should I have my last coffee?
In one study, 400 mg of caffeine 6 hours before going to bed took away more than an hour of sleep. If you go to bed at 23:00, the sensible approach is to avoid caffeine from mid-afternoon.
Is it bad for your sleep to train in the evening?
In general, no. A meta-analysis of 23 studies did not find that evening exercise worsened sleep. The exception is a hard effort that ends less than an hour before going to bed.
Which supplements help you sleep?
The most studied are glycine, L-theanine, tryptophan, magnesium and melatonin.
Sources
- Watson NF, Badr MS, Belenky G, et al. Recommended amount of sleep for a healthy adult: a joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society. Sleep. 2015;38(6):843-844. View publication
- Hirshkowitz M, Whiton K, Albert SM, et al. National Sleep Foundation's sleep time duration recommendations: methodology and results summary. Sleep Health. 2015;1(1):40-43. View publication
- Walsh NP, Halson SL, Sargent C, et al. Sleep and the athlete: narrative review and 2021 expert consensus recommendations. Br J Sports Med. 2021;55(7):356-368. View publication
- Mah CD, Mah KE, Kezirian EJ, Dement WC. The effects of sleep extension on the athletic performance of collegiate basketball players. Sleep. 2011;34(7):943-950. View publication
- Nedeltcheva AV, Kilkus JM, Imperial J, Schoeller DA, Penev PD. Insufficient sleep undermines dietary efforts to reduce adiposity. Ann Intern Med. 2010;153(7):435-441. View publication
- Drake C, Roehrs T, Shambroom J, Roth T. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. J Clin Sleep Med. 2013;9(11):1195-1200. View publication
- EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). Scientific opinion on the safety of caffeine. EFSA Journal. 2015;13(5):4102. View publication
- Stutz J, Eiholzer R, Spengler CM. Effects of evening exercise on sleep in healthy participants: a systematic review and meta-analysis. Sports Med. 2019;49(2):269-287. View publication
Information based on published studies. It does not replace the advice of a doctor or registered dietitian. The results describe what was measured in each study, not the properties of any specific product. A varied and balanced diet and a healthy lifestyle are important.
