Sleep Part 4: What Happens to the Body and Muscles While Sleeping

Sleep is an involuntary process that is required every single day by every single person. It’s an essential part of life and vital to the brain and body. Ultimately, the body could not function effectively without it. Everyone needs sleep regardless of goals. Active or not – sleep is a natural part of life. However, active adults and/or athletes should consider sleep alongside nutrition as part of their recovery routine. Contrary to popular belief, muscle recovery takes place beyond the few hours post-workout. Muscle recovery is an ongoing 24-hour process that can take up to several days. Meaning muscles are still recovering even while you sleep. So let’s take a closer look at what happens to the body and muscle while we sleep.

The Five Stages of Sleep

There are five stages of sleep that the body goes through each night and the brain will cycle through five stages of sleep several times throughout the night. In fact, the average healthy adult may cycle through the stages about four to five times each night. So what are the five stages? Stages one through four may be referred to as non-REM sleep, which account for about 75-80% of a night’s sleep. Stage one and two are often grouped together as they are known as the light stages of sleep. Stages three and four are also combined stages often referred to as synchronized sleep or deep sleep. Lastly, stage five is probably the most well-known stage of sleep known as rapid eye movement or REM. REM sleep accounts for approximately 20-25%. Each stage is associated with different processes that help the body recover both physically and mentally from the day before. Sleep is actually an incredibly complex process, but let’s take a closer look at some of the basics.

Non-REM Stage One. Lightest stage of sleep where the body is between being awake and falling asleep.

Non-REM Stage Two. Onset of sleep and the body becomes disengaged with surroundings; slower breathing pattern and heart rate and lower body temperature.

Non-REM Stages Three and Four. Beginning of deep sleep. During this stage, breathing and heart rate are at the lowest levels. Muscles relax and brain waves become slower. Blood supply to muscles increases and recovery can occur. This stage is imperative to anabolic processes such as muscle recovery.

REM Stage Five. REM sleep is the final stage of sleep. The first REM stage occurs in the approximately 90 minutes after falling asleep and recurs again approximately every 90 minutes, with this time getting longer as the night goes on. REM sleep provides energy to the brain and body and supports daytime performance. The brain is active and has exhibits brain waves, which are similar to those during wakefulness. Here is where dreams occur and it’s visible to an observer as they can see the closed eyes dart back and forth. In this stage the body becomes immobile and relaxed. After the REM stage ceases the other stages of sleep will repeat as long as you stay asleep.

Sleep Recommendations

As previously mentioned, sleep is required by all living beings. It is an important element all throughout each stage of life. It’s important to obtain sufficient high-quality sleep each night to help the body restore and to help support muscle recovery. The amount of sleep recommended depends on age. The National Sleep Foundation recommends that healthy adults sleep about seven to nine hours each night. The recommended ranges are good to abide by, however it’s important to understand your own body and needs. Determine how much you sleep you need according to how you feel. Some may feel that they need less than recommended or more – adjust accordingly so you feel renewed each day. But let’s not get carried away. Just like everything else in life – moderation and balance are key. That means more sleep is does not equal more muscle or additional recovery. However, inadequate sleep could impact the level of recovery and performance. So, next time you’re addressing your recovery routine – look beyond nutrition and hydration and factor in sleep.