Probably the most important part of the recovery cycle is sleep. But how many of us get enough of it?
The number one reason sleep is important is because the Human Growth Hormone (HGH) rises during deep sleep, which often begins about 30-45 minutes after falling asleep. HGH (also known as Somatotropin) is an amino acid produced in the pituitary gland of the brain. This plays an important role in human development by affecting skeletal growth.
Certain sleep conditions release HGH. In men, 60% to 70% of daily human growth hormone secretion occurs during early sleep which is typically when the deepest sleep cycles occur. Poor quality rest can negatively impact human growth hormone levels.
Another reason sleep is so important is Cortisol levels, the stress hormone. When your body is not getting enough sleep cortisol levels rise. This effects the body in dramatic negative ways including:
- High cortisol decreases immunity. Cortisol is a corticosteroid and like prednisone, cortisone, and beclomethasone, it inhibits the actions of white blood cells. Initially, this usually leads to increased susceptibility to infections. Eventually, this may actually lead to long stretches of time without colds because the immune system is so weakened.
- High cortisol increases abdominal fat deposition. For reasons still unknown, high levels of cortisol induce the body to lay down adipose tissue in the abdomen and upper back/neck. In fact, for those people affected it is next to impossible to lose abdominal fat without addressing stress.
- High cortisol breaks down muscle, bone, and connective tissue. Cortisol is a gluconeogenic hormone. Gluconeogenesis is a process that creates sugar from existing tissue. Cortisol promotes the breakdown of muscle, bone, and connective tissue in order to increase blood sugar for the brain.
- High cortisol inhibits thyroid hormone activation. The thyroid gland makes 2 major hormones; thyroxine (T4) and triiodothyroine (T3). It predominantly makes T4, which is actually an in-active hormone. T3 effects how much fat your body stores and how much it flushes out. The higher the cortisol the more fat that will ultimately get stored!
Generally, 6 to 9 hours of sleep is sufficient. As long as you feel rested the next day, then you've achieved your goal of getting enough rest.