Sleep. Yes, the one word we know we all need but can’t find the time to get it. The question is, why is sleep so important? What does it do for the body?
What is sleep? Sleep can be defined as being a state of partial consciousness from which a person can be aroused via a stimulus. This is in contrast to a coma, from which a person cannot be aroused. (Marieb, Elaine N. and Hoehn, Katja, Human Anatomy and Physiology, 8th ed., San Francisco, Pearson Education Inc., 2010. Print) When a person is sleeping, their body is pretty much entirely controlled by the autonomic nervous system, or the involuntary aspects of the nervous system. There are different stages of sleep, the most famous being REM (rapid eye movement) sleep, but there are others. Here is a diagram of the different stages of sleep:
Why do we sleep? Sleep is vital to a person’s health. When a person is sleep deprived, their mood changes. The longer a person goes without sleeping, the worse it gets. After a few days of no sleep, a person may begin hallucinating. Sleep is important for all aspects of life. As a person sleeps, the body works to support healthy brain function and maintain physical homeostasis (body equilibrium). Deep sleep triggers the body to release growth hormone (GH) which affects the growth of the body (https://www.nhlbi.nih.gov/health/health-topics/topics/sdd/why). This is part of why babies need so much sleep- their bodies have so much development to do, so they need more sleep. GH stimulates most body cells to increase in size and divide, but its major targets are the skeletal muscles and bones. GH causes long bones to grown and it stimulates increase in muscle mass. A summary of the effects of GH can be found in the following chart:
How much sleep is necessary? The answer to this question varies with each person, but in general, the following chart can be followed:
|Age||Recommended Amount of Sleep|
|Newborns||16–18 hours a day|
|Preschool-aged children||11–12 hours a day|
|School-aged children||At least 10 hours a day|
|Teens||9–10 hours a day|
|Adults (including the elderly)||7–8 hours a day|
As you can see, infants need a lot of sleep. This is in order for their bodies to grow and develop properly.