Recovery and Sleep

Sleep and return to homeostasis

As a healthy adult, you will spend about one-third of your life asleep. The daily need for at least some sleep and the body’s forceful somnolent reminders when we ignore its circadian requirements tend to overshadow the amount of thought or effort we put into our sleep habits as a form of recovery. What food, air, and water are to our physical functioning, sleep is to our mental state. Without it, our higher brain functions decline. Though it’s not clear how long a person can survive without sleep, severe side effects of an acute loss of sleep can occur in as little as 36 hours of deprivation. The longest recorded voluntary loss of sleep is 11 days. You can survive on no sleep, but after just a few days of sleep deprivation, you would likely experience varying levels of cognitive impairments, hallucinations, irritability, delusions, paranoia, and psychosis.

Such acute losses of sleep are rare in healthy individuals. This is because sometime after 36- 72 hours, the urge to sleep is nearly irresistible. Many people, however, suffer from chronic sleep loss. Whether this is voluntary, due to lifestyle or habits, or caused by a medical disorder such as obstructive sleep apnea or depression, chronic sleep loss is a common problem and one that affects much more than your mental health. The CDC estimates that one in three adults do not get enough sleep.  The effects of chronic sleep deprivation extend beyond sleepiness and impaired cognitive function to an increased risk for

• Heart disease
• Heart attack
• Heart failure
• Irregular heartbeat
• High blood pressure
• Stroke
• Diabetes

Most of us understand, at least intuitively, that sleep is necessary for our basic functioning. But what about training? Professional and highly competitive athletes swear by their sleep. If we spend so much time in the gym, lifting weights, and trying to get stronger, what role does sleep play in our results? And, if you are already getting 8 hours most nights, is there really anything else for you to consider when it comes to sleep? To answer some of these questions, let’s first define sleep.

What is Sleep?

Often we will think of sleep as a negative state, defined by what it isn’t, being simply a state of reduced consciousness, reduced activity, and reduced functions. In that way, it can be tempting to think of sleep as a state of extreme rest. But in his book “Sleep,” dream researcher Allan Hobson described sleep as an active state: “[S]leep is a “dynamic behavior. Not simply the absence of waking, sleep is a special activity of the brain, controlled by elaborate and precise mechanisms. Not simply a state of rest, sleep has its own specific, positive functions.” (Allan Hobson, “Sleep,” Scientific American Library Series(1989).) Sleep is not just a more complete rest; some things take place during sleep that do not take place during any other state of wakefulness or unconsciousness.

Sleep is a homeostatically controlled process. It has been understood as necessary, at least since Aristotle’s time. Its necessity comes from the physical and mental restorative mechanism of the different sleep phases. “Recent Studies have shown sleep to regulate key molecular mechanisms (i.e., transcriptional regulatory proteins ), and have demonstrated that sleep has an integral role in metabolic homeostasis.” (Hugh H.K. Fullagar, “Sleep-Related Issues Facing Professional Football Players,” Institute of Sport and Preventative Medicine: 20 (Thesis 2017.)

Sleep can be divided broadly into two phases. Rapid Eye Movement (REM) and Non-Rapid Eye Movement (NREM). These phases occur in order: NREM comes first in three stages, progressing to REM sleep. The three NREM stages take you from lighter to deeper states of sleep. (Fullagar (noting that the three stages of NREM sleep used to be considered four separate stages); see also Venter (“Researchers often refer to the combined stages three and four sleep as slow-wave sleep or deep sleep.”))[1]

Stage 1 NREM: Light Sleep

• Light sleep
• Easy to wake
• Short duration, lasting 1 to 7 minutes

Stage 2 NREM: Reduced Wakefulness

• Reduced wakefulness
• No eye movement
• Short duration, lasting 10 to 20 minutes

Stage 3 NREM: Slow-wave; Deep Sleep

• Decrease in blood pressure and heart rate
• Lasting about 20-40 minutes
• No eye movement

After 30 to 40 minutes, you enter REM sleep, or “Dream sleep.” Here, “The brain reactivates into a fast-activity state. Blood flow, heart rate, respiration, body temperature, and blood pressure of the person rise, and the eyes, underneath closed eyelids, dart back and forth as if scanning the environment, which may be accompanied by intermittent small muscle twitching.” (Venter) REM sleep is thought to be critical for memory, motor learning, and establishing brain connections. This may be important when you are learning new motor skills like squatting, pressing, and deadlifting, but most of the processes of REM sleep suggest that it is for the restoration of the brain and not so much of the body.

However, during NREM sleep, there are significant happenings that may affect your physical recovery from training, restoring damaged muscles, and building new muscles. “Although the body is continually in a process of revitalization, this process peaks during stage-three and stage-four sleep. Physiological processes that cause this effect during slow-wave sleep are facilitated by metabolic activity being at its lowest at this point, as well as increased secretion of growth hormone by the endocrine system.” (Venter, (citing Walters, “Sleep, the athlete, and performance,” National Strength & Conditioning Association, 24(2): 17-24 (2002); Loehr & Schwartz, “The power of full engagement,” New York, NY: Free Press (2005).) While this is a process that will occur whether you train or not, it seems that a loss of sleep and, therefore, the lost opportunity for restoration and growth would negatively impact both your preparation for future training and the benefits you get from lifting in the first place.

Many factors will positively and negatively affect this secretion of growth hormone; sleep is a key one. “The most powerful, non-pharmacological stimuli to initiate the secretion of growth hormone are sleep and exercise” (Venter, citing Godfrey, Madgwick, & Whyte, “The exercise-induced growth hormone response in athletes,” Sports Medicine, 33(8): 599-613 (2003).) When you train, you stimulate an anabolic hormonal response. When you train and sleep, you encourage that response, which helps restore your muscles and helps you build new muscle in response to the stress of training.

However, researches have observed that the secretion levels, which you tried so hard to stimulate through training, fall significantly when athletes lose slow-wave sleep. (Davenne, “Sleep of athletes: Problems and possible solutions,” Biological Rhythm Research, 40(1): 45-52 (2009).) Other factors that will impact this secretion include “age, gender, body composition, sleep, nutrition, exercise and serum concentrations of gonadal steroids, insulin and IGF-1.” (Zając et. al, “Effects of Growth Hormone Therapy and Physical Exercise on Anaerobic and Aerobic Power, Body Composition, Lipoprotein Profile in Middle-Aged Men,” Journal of Human Kinetics, vol. 25: 68 (2010).)

Getting enough sleep is a lifestyle factor that will benefit your training. Sleep helps you retain cognitive function, energy, and motivation and allows the recovery processes to run at their full potential. Sleeping enough means just getting out of your own way. And who doesn’t love a good nap anyway?

Sleep Best Practices

The problem is many of us do not sleep enough, and even among those who manage the standard 8 hours, many aren’t getting quality sleep. With regard to sleep volume, you may take hours away from sleep for other activities—sometimes even training. This isn’t something you can always avoid, but if you care about your strength training activities, you should fight to preserve your sleep. Most experts recommend 7 to 9 hours of sleep per night. In their book on periodization and training, however, Bompa and Haff argue that athletes need more sleep, suggesting 9 to 10 hours of sleep, 80-90% of it during the night. They advocate power naps to cover the remainder.

Hours-per-night is just one part of good sleep. Quantity cannot make up for poor-quality sleep. And quality sleep comes from your sleep habits, schedule, and environment. These are perhaps doubly important if you consistently sleep fewer than the recommended hours.

For sleeping habits, there are lifestyle factors that can help or harm your sleep. “Many people are aware that they need a period of relaxation between the concerns and psychological stressors of the day and their major or nocturnal (night) sleep. Athletes should be encouraged to follow a bedtime ritual and develop a ‘winding-down routine’ that serves as a cue to the mind and body to get ready for sleep.” (Reisser, “Overcoming fatigue: In pursuit of sleep and energy,” (Tyndale House 2006).) Just like we tend to do for children, establishing a nightly routine that allows you to wind down before you actually get in bed will help improve your nightly quality of sleep. This also includes alcohol and caffeine, either of which can impair your sleep quality. (Venter)

Just as with training, consistency is necessary for good sleep. This can be difficult, but going to bed at the same time and waking up at the same time prepares your body for sleep and improves your sleep-wakefulness cycle. You train your body to go to sleep more easily at bedtime than if you are constantly shifting your sleep schedule. Getting up at the same time is important, too, it is recommended that athletes get up at the same time even if they have poor sleep the previous night to help establish and maintain their sleep schedule. (see Reisser.)

Finally, your sleep environment can affect your sleep quality. Avoid sleeping upright or in excessively hot or cold environments. You should reduce the amount of ambient light and noise as much as possible. In particular, non-continuous noise, such as traffic noise, has been shown to be the most disruptive to sleep. Even life stress can disrupt your sleep, so anything you can do to relax before bed can help you improve your sleep.

What should you do if you’ve accrued “sleep debt,” having missed good quality sleep for days, weeks, or even years? You can pay off this kind of sleep debt, but doing so seems to require some dedicated effort. Most sources suggest that chronic sleep loss will not be reversed with just a few extra hours on the weekend. However, a few days of extra sleep and better habits will get you back on track. Two researchers have suggested that “the best way to achieve sleep requirements is to go to bed when tired and sleepy and get up in the morning feeling refreshed, without any alarm, for a few days.” (Venter (citing Bonnet & Arand, “Should we be taking more sleep?” Sleep, 18: 908-911 (1995)).)

Resources in this article

[1] All references are cited in-line above, but Rachael Venter’s “Role of sleep in performance and recovery of athletes: A review article,” South African Journal for Research in Sport, Physical Education and Recreation (January 2012) (available at https://www.researchgate.net/profile/Rachel_Venter/publication/230582637_Role_of_sleep_in_performance_and_recovery_of_athletes_A_review_article/links/00b49519f10fdc7361000000/Role-of-sleep-in-performance-and-recovery-of-athletes-A-review-article.pdf) provided most of the other books and research.

Also, BOMPA, T.O. & HAFF, G.G. “Periodization: Theory and methodology of training,” Champaign, IL: Human Kinetics (5th ed. 2009) provides an excellent discussion of recovery as in the context of athletics and periodized training.

[2] Aristotle, “Sleep and Sleeplessness”:

We have now stated the cause of sleeping, viz. that it consists in the recoil by the corporeal element, upborne by the connatural heat, in a mass upon the primary sense-organ; we have also stated what sleep is, having shown that it is a seizure of the primary sense-organ, rendering it unable to actualize its powers; arising of necessity (for it is impossible for an animal to exist if the conditions which render it an animal be not fulfilled), i.e. for the sake of its conservation; since remission of movement tends to the conservation of animals. -“Sleep and Sleeplessness”