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Exercise & Sleep | The Effect On Performance

How Does Sleep Effect Progress?

When it comes to training, often times we overlook the factors of sleep on our body. We don’t really look at sleep and training as to be interconnected with one another, instead, most of us just simply know that when we lack sleep and become tired, our training to follow that day will be a little tougher and more physically demanding in part of a lack of energy. To some, we may combat this with a pre-workout, coffee/caffeine stimulant, or an increase in food for the day. What we should be doing is finding out how to fix the issue in regards to sleep and training for optimal results and health.


Studies have been shown that training later in the day compared to earlier training sessions will release more melatonin within the body. Melatonin is a sleep hormone our body naturally produces. Meanwhile, exercising later in the afternoon or evening will make it harder for one to go to sleep. This is in part due to the bodies “flight or fight” or sympathetic nervous system responding to the training. Because of the level of increased intensity at this later time, your body will release less melatonin (sleep hormone) as well as also increasing alertness due to the sympathetic nervous system is more active. What this means is that by training later on the day, your body will become more alert and delay the release of melatonin within the body, resulting in making it harder to fall asleep and a lower quality of sleep as well. To combat this, its best to perform your training either in the morning or earlier in the afternoon to avoid the late night training sessions.

sleep and muscle growthHow Does This Effect Energy Levels?


When our body lacks an adequate amount of sleep, regardless of if we are exercising or not, we will eventually become tired and have low energy if the pattern continues for days on end. This is natural for everyone no matter what fitness condition you are in. When the body lacks sleep it can actually increase the amount of cortisol found in the body. Cortisol is a stress hormone that the body naturally produces in the adrenal glands that helps the body convert sugar (glucose) and fat for energy to maintain a healthy metabolism. What this means is that by lacking sleep, the body’s natural cortisol levels will increase.

This will do 2 main things: 1) it will increase the “flight or fight” symptoms in the body, and 2) it will increase the amount of glucose (sugar) the body produces which can lead to an increased level of blood sugar levels. Although an increase in blood cortisol levels for a short period of time will not have any impact on your body, an increase of cortisol for a longer-term, however, can have an impact on the body’s ability to produce lean muscle tissue. In fact, a high level of cortisol will actually lead to the muscle being broken down resulting in a loss of strength and muscle mass.

sleep and muscle growth

Will This Effect Weight Loss?

Another thing many people overlook with sleep in regards to training is that it can actually prevent weight loss. This is actually due to many reasons, all of which are the result of lacking sleep. By being sleep deprived our brain can make bad decisions since we are tired and are requiring more energy to function. The body will combat this first by slowing down activity in the brain in regards to decision making and control, which results in cravings of foods we shouldn’t be eating. Its similar to being drunk and not actually having the mental clarity to make better decisions in a sense. Lacking sleep can also lead to the increase in specific food cravings, most foods high in carbs and sugar, which are actually very energy dense.


What this means is that you will crave and eat foods that can negatively impact your diet and results, while also causing more damage to your energy and sleep levels as compared to “healthier” and more energy-rich foods. You might notice that when you are really tired you’re actually hungrier compared to usual. This is because when we lack sleep, the body will increase production of the hunger hormone ghrelin (this tells the brain we need to eat) while also suppressing the release of leptin (the hormone responsible for telling the body its full from food and to stop eating). Combine these two hormones together and you end up with the brain telling you to not only eat food but to also eat more while not providing control on when you’re actually full and satisfied.


In simple terms, lacking sleep will have a negative impact on your hormones and weight loss goals from causing you to eat more, not recognizing you are full, increasing cravings, slowing down hormones and metabolism, and eventually decreasing overall energy your body will have throughout the day which makes the days harder physically and mentally on yourself. Its important to sleep anywhere between 6-8 hours or so a night while also eating healthy fats to help prevent the increase of hunger.

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Faye Reid

Faye Reid

Writer and expert

Faye Reid has a Master of Science in Sport Physiology and Nutrition. She puts her passion into practice as goal attack for her netball team, and in competitive event riding. Find out more about Faye's experience here: https://www.linkedin.com/in/faye-reid-8b619b122/.

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