The Impact of Sleep on Body Composition
Written by Connor Nellans
Anecdotally, we all know how much we are impacted by lack of sleep or poor quality sleep. When we do not get enough sleep, we don’t feel like ourselves. We feel sluggish – both physically and mentally – and our motivation to get into the gym and to make positive nutrition choices becomes diminished. We all know the importance of sleep because of how we feel when we do not get adequate amounts, but what is really going on in our body and how does sleep impact our body composition goals?
Sleep & Body Composition
As it turns out, sleep is one of the most important factors when it comes to positively changing our body composition. Whether your goal is to increase Lean Body Mass (through increasing skeletal muscle), lose body fat, or a combination of the two, quality sleep is an incredibly important piece of achieving these goals.
When trying to increase Lean Body Mass, it is important to optimize our bodies natural ability to produce our anabolic (muscle growing) hormones (1). The first hormone that we must consider when trying to increase skeletal muscle is Growth Hormone (GH).
Sleep, Muscle Development & Recovery
Research has shown that 70% of GH is released during our deep sleep cycles (2), which take about 90 minutes to occur. So in order to optimize our bodies release of GH during sleep, we would need 7 ½ hours of sleep for five 90-minute cycles to occur. Thus, if we are not getting at least 7 ½ hours of sleep each night, we are missing out on potential GH release in the body and in return missing out on potential skeletal muscle growth.
The second anabolic hormone that is heavily linked to sleep is testosterone. In both sexes, testosterone production will increase in the body when they exercise, this promotes muscle development and recovery (3). In much the same way as growth hormone, testosterone secretion has been heavily linked to deep sleep, and research has shown that sleeping 5 hours or less leads to a 10-15% decrease in the amount of testosterone your body will produce while sleeping (3).
Lack of Sleep & Cortisol
Besides dappening the release of anabolic hormones, lack of sleep also can lead to an increase in the amount of catabolic hormones our body produces, specifically cortisol. Cortisol is released in the body to break down tissue to be used as energy in response to stress. Research has shown that during sleep deprivation cortisol levels can increase by 37-45% the following evening (4). This does not spell good news for increasing lean body mass, especially when combined with the decreased release of our anabolic hormones, growth hormone and testosterone.
In conclusion, a lack of sleep can cause our bodies to produce and release less of the anabolic hormones that positively impact our body composition through muscle growth and recovery. Further, missing out of sleep can cause our body to produce more cortisol which leads to increased muscle break down. By missing out on sleep, we are also missing out on skeletal muscle growth and increased lean body mass while potentially reversing our progress through increased cortisol in the body.
Thus, I encourage everyone to get at least 7 ½ hours of quality sleep per night! To make sure the sleep you are getting is quality, put up black out shades in your room to keep it as dark as possible, put screens away one hour before sleeping, keep your room cool, and turn off or cover any small lights in your room. Protect your sleep and start seeing the positive results carry over into your body composition goals! Looking for more positive body composition changes in your life? Join our online Nutrition Program with coaches Connor Nellans and Jenn Ryan!