How to Sleep Properly: 4 Negative Side Effects of Inadequate Sleep

Pete McCall
Pete McCall
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No one is born knowing how to exercise. It is a subject that must be studied and understood correctly to do it properly. Earning the Certified Personal Trainer credential from the National Academy of Sports Medicine (NASM) means that you can design exercise programs to help clients reach their goals safely and efficiently.

Exercise is not the only factor that can help a client to achieve his or her goals. However, it’s also essential to coach clients on improving nutrition and practicing other lifestyle habits that can support their efforts in the gym.

There is one healthy lifestyle habit that your clients are already doing, but the chances are that if they aren’t doing enough of it, their efforts in the gym or the time spent on proper nutrition won’t produce the desired results. Achieving results from exercise requires getting the optimal quality and quantity of sleep.

“I’ll get enough sleep when I’m dead” is a common sentiment stated by people who fill their schedules with both work and social commitments.

Still, the reality is that not getting enough sleep could result in an early death making it a self-fulfilling prophecy. Evidence suggests that insufficient sleep is a risk factor for several chronic health concerns, including obesity, onset diabetes, cardiovascular diseases, depression, and impaired driving (Channaoui, et al. 2014).

Let's explore below.

4 negative side effects of getting inadequate sleep

1. The National Sleep Foundation, an organization of doctors and researchers who specialize in sleep, recommends that adults achieve between 7 to 9 hours of sleep per night (Sleep Foundation, 2020). Consider this, increasing sleep time by an hour per night is like getting an entire extra night’s worth of sleep over a week.

2. For both men and women, sleeping less than 6 hours per night could result in higher belly fat levels. A lack of sleep can elevate the sympathetic nervous system (SNS), responsible for stimulating the metabolism to produce the energy for physical activity. Insufficient sleep could boost the hormones cortisol and epinephrine, which help release free fatty acids that we use for energy. When there is low physical activity, the free fatty acids can deposit in the adipose tissue of the abdominal region resulting in additional belly fat (Kenney, Wilmore and Costill, 2015). 

With this in mind, check out 5 ways to SPEED up metabolism. #1 is sleep!

3. Another way that insufficient sleep could lead to weight gain is through the production of specific hormones. Grehlin is a hormone responsible for stimulating hunger. Leptin performs the opposite function and tells the body when it has had enough food intake. We associate poor sleep with an imbalance in these hormones, potentially resulting in over-eating (Chennaoui, et al. 2015). Plus, staying awake late into the evening allows more opportunities for mindless snacking on calorically-dense food.

4. Insufficient sleep could impair the body’s ability to properly recover from a challenging strength training workout designed to promote hypertrophy. Growth hormone, an anabolic hormone responsible for repairing muscle tissue damaged during exercise, is produced during stage 3 of NREM sleep; achieving optimal sleep could be helping muscles grow (Channaoui, et al. 2014).

Read also: The Importance of Sleep and Recovery

Ways to Sleep Properly

Despite the amount of research on the subject, scientists and medical professionals who study sleep are not 100% sure why we need rest. Still, based on the evidence, it is well established that achieving optimal sleep is essential for long-term health.

The National Sleep Foundation provides the following suggestions for how to improve sleep habits (Sleep Foundation, 2020):

• Keep a regular sleep schedule. Try to go to bed at the same time every night.

• Sleep in a dark room, remove the television and leave electronic screens in another place. The bedroom should be for sleeping, not watching television.

• Don’t eat right before bed. Digestion could interrupt the process of falling asleep.

• Reduce overall levels of stress. Easier said than done. Still, regular exercise plays a vital role in reducing overall stress levels, and that is where your role as NASM-Certified Personal Trainer is crucial.

The Sleep Cycles

While snoozing, the body will experience multiple cycles of sleep, each of which can last between 70 to 120 minutes; there are three stages of non-Rapid Eye Movement (NREM) sleep and a fourth stage of Rapid Eye Movement (REM) sleep (Bushman, 2013).

• Stage 1 Non-REM: the body has just dozed off and is preparing to enter stage 2; it can last between one-to-five minutes.

• Stage 2 Non-REM: the body is essentially ‘powering-down’ by reducing activity in the brain and body; this stage can last between ten and sixty minutes.

• Stage 3 Non-REM: brain activity slows down and relax; this stage can last between twenty and forty minutes.

• Stage 4 REM: activity in the brain increases while most of the body experiences temporary paralysis so that your muscles don’t react to any visual stimulation you may experience while dreaming; REM can last between ten and sixty minutes.

Understanding Circadian Rythms

The body’s circadian rhythms control functions such as temperature and sleep. As the sun goes down, the circadian rhythms will naturally start preparing the body for sleep; exposure to light sources such as electronic screens, a stressful situation, hunger, or substances such as caffeine, sugar, or alcohol could interrupt the body’s ability to transition to sleep.

Melatonin is a hormone that is supposed to help the body transition to sleep as exposure to light decreases, which explains why trying to reduce screen time later in the evening is so essential for optimal sleep. (Sleep Foundation, 2020).

The Role of a Certified Personal Trainer in Suggesting Healthy Sleep Patterns

The role of a NASM-certified personal trainer is to raise a client’s awareness about how to improve healthy habits like getting adequate sleep. One way to help clients achieve better sleep is to help them plan their workouts based on the sleep they’ll get at night. For example, during a warm-up, ask a client about his or her planned night-time activities.

Suppose the client indicates that they have plans like attending a concert, hitting a nightclub, or partying with friends. The chances are they will go to bed later than usual and may not get the recommended seven-to-nine hours of sleep. Therefore it would be good to do a lower-intensity workout that will place less stress on the body. However, if the client indicates no specific plans other than a quiet night at home, they can do a more intense workout because they will more than likely get a good night’s sleep.

Asking about evening plans and relating them to sleep quality can help demonstrate additional value and show that you can help your clients get the best results from their workouts. After a while, your clients should understand the relationship between exercise and sleep and will start making their evening plans accordingly. Here’s the excellent news, as clients improve their sleep habits, they could start seeing better results from their workouts, and you will be the one who receives the credit for that outcome.


As a personal trainer, it is entirely appropriate to have a conversation about sleep with your clients. The reality is that sleep is a critical component for achieving optimal health. If you have clients working hard on their exercise program and watching their nutrition intake yet still not seeing the results they want, it may be necessary to look at their sleep habits.

Helping clients improve their sleep habits could help save their lives. Too much exercise and too little sleep could result in overtraining and keep a client from reaching his or her goals.


“How Sleep Works: Understanding the Science of Sleep.” Sleep Foundation, 29 Nov. 2020,

Bushman, B. (2013) Exercise and Sleep. ACSM’s Health & Fitness Journal. 17(5). 5-8.

Chennaoui, M., Arnal, P., Sauvet, F. and Leger, D. (2014) Sleep and Exercise: A Reciprocal Issue? Sleep Medicine Reviews. 20. 59-72.

Kenney, W., Wilmore, J. And Costill, D. (2015) Physiology of Sport and Exercise, 6th edition. Human Kinetics: Champaign, IL.

The Author

Pete McCall

Pete McCall

Pete McCall is a NASM-CPT, PES, Certified Strength and Conditioning Specialist (CSCS), international presenter, host of the All About Fitness podcast, fitness blogger and an author of several articles, textbook chapters and the book Smarter Workouts: the Science of Exercise Made Simple. In addition, Pete holds a master’s degree in exercise science and has been educating fitness professionals for more than 15 years. Currently Pete lives in Encinitas, CA where he is an education consultant and content creator for Core Health & Fitness, Terra Core Fitness and 24 Hour Fitness.


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