Get Some Sleep

How resting at night helps the body, brain and consciousness recover.

by Charlie Hoolihan

Imagine you’ve found a training program scientifically guaranteed to promote weight loss, build muscle, and improve reaction time, cardiovascular function and mental clarity. There’s only one catch: The program requires your clients to reduce their weekly training hours with you. Would you even consider recommending it?

Few trainers or coaches would suggest a regimen that would undermine the health of their business. And yet, fit pros could undermine the health of their clients by advising them to cut back on sleep to find more time to train. Sleep is fundamental to healing the tissue damage of exercise. Clients who don’t get enough rest face a greater potential for illness, injuries and stalled progress.

Instead of advising clients to wake up an hour earlier 3 days a week, explain why reinforcing the importance of getting enough sleep could be the missing variable in their training program. This article addresses the inherent value of sleep and looks at the limits of sleep science.

Understanding Sleep Patterns

Sleep experts seem to agree that a broad range of 7–9 hours of sleep per night creates an optimal window for complete physical, mental and emotional restoration. Less than 6 hours per night, however, dramatically increases the chances of negative health conditions (Ohayon et al. 2017; Assefa et al. 2015).

In a good night’s sleep, we cycle four or five times (or more) through various stages of sleep, each with specific qualities and purpose. A cycle lasts 70–90 minutes. These stages and cycles of sleep are just as important as overall sleep duration (if not more so). They all have restorative properties, and we need to spend a relatively equal amount of time in each stage (Winter 2018; Ohayon et al. 2017).

Three Phases of Sleep

For the purposes of this article, sleep can be grouped into three phases:

  • LIGHT SLEEP, a transitional phase that mainly serves to settle the body into sleep;
  • DEEP SLEEP, also called SLOW-WAVE SLEEP in which most physical recovery takes place; and
  • REM (RAPID EYE MOVEMENT) SLEEP, which seems to provide for mental recovery.

Scientists identify these phases by measuring physiological variables such as electrical brain activity, blood pressure and eye movement. Brain waves offer the most definitive demarcation points because they are more consistently identifiable (Winter 2018; Ohayon et al. 2017)

Light Sleep

Light sleep consists of stages 1 and 2 of non-REM sleep. NREM 1 transitions us from wakefulness to sleep and lasts only a few minutes. Heartbeat, breathing and eye movements slow, and our muscles begin to relax. NREM 2 is still light sleep, but relaxation deepens, heartbeat slows further and body temperature drops.

Deep Sleep

Deep sleep takes place in stage 3 of non-REM sleep. In NREM 3, heartbeat and breathing slow to their lowest levels of the night. Likewise, brain waves become slow, and muscles are very relaxed (NINDS 2018).

Deep sleep conserves energy and rests the body’s physiology. Restorative hormone activity increases: The release of growth hormone and other anabolic hormones boosts protein synthesis and tissue regeneration, while inflammatory and catabolic hormones are suppressed (Samuels 2008; Chennaoui et al. 2015; Fullagar et al. 2015).

REM Sleep

In REM sleep, which first occurs about 90 minutes after falling asleep (NINDS 2018), brain activity is more akin to that of a waking state. The hallmark rapid eye movements occur, blood pressure increases, and respiration speeds up (Kanda et al. 2016; Assefa et al. 2015; Winter 2018). It has been suggested that the brain and conscious mind recuperate during this active, dream-rich phase of sleep. A recent study discovered that the brain has a toxin-removal system that is activated during REM sleep (Assefa et al. 2015; Winter 2018).

Confronting Voluntary Sleep Restriction

Sleep restriction—cutting back to accomplish a goal—is fairly common in the fitness universe. Getting up earlier than usual to squeeze in a workout or add a second daily training session is prevalent, but it can trip up sleep patterns in ways that create potential health hazards (Assefa et al. 2015; Winter 2018; Kendall-Tackett 2010).

The key for fit pros is to help their clients optimize their sleep patterns to improve performance. That means considering sleep habits along with other training variables.

Establishing Individual Parameters

There are no hard-and-fast guidelines for how much sleep is sufficient, so each client must determine what is best for him or her. You can get a good idea of a client’s optimum sleep pattern during an “offseason” or easy training cycle, when sleep restriction is not necessary. Ask your client to go to bed at the usual time and wake up without an alarm. Doing this for a week or so will normalize sleep needs, and the optimal number of hours should become apparent. This number can serve as the client’s baseline (Winter 2018; Dement 2001).

Note that most of us have a built-in sleep/wake cycle called a circadian rhythm that responds to light and dark. This cycle will also become evident during the baseline examination. Circadian rhythm is just as important as sleep duration. Resetting this rhythm takes more effort than simply going to bed earlier when alarm-based, early-morning waking becomes a necessity again (Dement 2001; Winter 2018).

When possible, try to respect sleep duration and circadian rhythms, and structure training sessions around those needs (Samuels 2008).

Sleep Restriction Remedies

Since training is not most people’s sole priority, you may be able to pair restrictions with “catch-up” sleep if training requirements cut into snooze time. A recent study found that the increased inflammatory markers caused by 4- and 6-hour nights of sleep returned to baseline after three nights with 9–10 hours (Killick et al. 2017).

Try to limit other inflammation sources like diet, workout intensity, work/school stress and recovery rates during programmed sleep restrictions (Thorburn, Macia & Mackay 2014; Kendall-Tackett 2010). For example, avoid restricting a student’s sleep in March during exam week or an accountant’s sleep in April at tax time.

Naps can normalize inflammatory markers, but how often people should nap and for how long depends on the individual. Recommendations for nap times range from 20 to 90 minutes, but the research is inconclusive (Faraut et al. 2015a; Faraut et al. 2015b; Milner & Cote 2009).

It’s important to note here that most research into performance parameters and sleep requirements is limited, but most agree that the inflammatory nature of physical training requires even more sleep.

Sleep Hygiene—Preparation and Environment

Establishing individual sleep parameters is a great start, but you also need to ensure a proper sleep environment. The recommendations below come from The Sleep Solution (Berkley 2018) by Chris Winter, MD

  1. Establish a consistent bedtime routine that promotes sleepiness, such as taking a warm bath, reading from a book and turning the lights out at a regular time.
  2. Avoid reading from a tablet or cellphone. The light from these devices appears to slow the production of melatonin, the hormone that initiates sleep.
  3. Write down thoughts in a notebook before bedtime to symbolically clear them from your mind.
  4. Create an extremely dark sleep space. Darkness stimulates melatonin production.
  5. Find a comfortable mattress with cozy bedding that suits individual preferences.
  6. Avoid consuming foods or drinks that can interfere with sleep. Products containing stimulants are obvious, but also be careful about alcohol: It helps people fall asleep, but when the body starts metabolizing alcohol midway through the night, sleep disturbance becomes rampant.
  7. Take the timing and type of meals into account. Generally, it’s best to eat dinner more than 3 hours before bedtime. High-carbohydrate foods stimulate sleepiness, while high-protein foods have the opposite effect.

Considering the multitude of health benefits from proper sleep, trainers and coaches should take time to educate clients and athletes about sleep’s critical link to performance. That means becoming more attuned to their individual sleep requirements.


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Dement, W.C. 2001 The Promise of Sleep: A Pioneer in Sleep Medicine Explores the Vital Connection Between Health, Happiness, and a Good Night’s Sleep. New York: Dell Trade.

Chennaoui, M., et al. 2015. Sleep and exercise: A reciprocal issue? Sleep Medicine Reviews, 20, 59–72.

Faraut, B., et al. 2015a. Napping reverses increased pain sensitivity due to sleep restriction. PLOS One, 10 (2), e0117425.

Faraut, B., et al. 2015b. Napping reverses the salivary interleukin-6 and urinary norepinephrine changes induced by sleep restriction. The Journal of Clinical Endocrinology & Metabolism, 100 (3), E416–26.

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Kendall-Tackett, K.A. (Ed.). 2010. The Psychoneuroimmunology of Chronic Disease: Exploring the Links between Inflammation, Stress, and Illness. American Psychological Association. Washington, D.C.: APA.

Killick, R., et al. 2017. Metabolic and hormonal effects of ‘catch-up’ sleep in men with chronic, repetitive, lifestyle-driven sleep restriction. Clinical Endocrinology, 83 (4), 498–507.

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Milner, C.E., & Cote, K.A. 2009. Benefits of napping in healthy adults: Impact of nap length, time of day, age, and experience with napping. Journal of Sleep Research, 18 (2), 272–81.

NINDS (National Institute of Neurological Disorders and Stroke). 2018. Brain basics: Understanding sleep. Accessed Aug. 16, 2018:

Ohayon, M., et al. 2017. National Sleep Foundation’s sleep quality recommendations: First report. Sleep Health, 3 (1), 6–19.

Samuels, C. 2008. Sleep, recovery, and performance: The new frontier in high-performance athletics. Neurologic Clinics, 26 (1), 169–80.

Thorburn, A.N., Macia, L., & Mackay, C.R. 2014. Diet, metabolites, and ‘western-lifestyle’ inflammatory diseases. Immunity, 40 (6), 833–42.

Winter, W.C. 2018. The Sleep Solution: Why Your Sleep Is Broken and How to Fix It. New York: Berkley.

Meet our experts

AFM_Author_Hoolihan Charlie Hoolihan, is a NASM-certified personal trainer with more than 40 years’ experience training athletes at all distances of competition, from swimming and track sprints to Ironman triathlons. Contact him at

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