BY Frank Spinelli, M D
July 20 2011 5:00 AM ET
We all have an internal clock that relies on circadian rhythms, providing clues to tell your body when it’s time to go to sleep and when it’s time to wake up. This clock is sensitive to the actual time of day. Light tells the body to wake up and darkness tells the body when it’s time to go to bed. When you fall asleep, your brain and body go through cycles throughout the night. The cycle alternates from alert stages to deep restorative sleep and dreaming. As the night progresses, you spend more time dreaming and in a lighter stage of sleep.
Getting good, restorative sleep is not just a matter of getting into bed and waking up in the morning. Your sleep cycle is regulated by specific sleep stages that are vital to your body. Understanding these stages may help you to understand how you can improve your quality of sleep.
There are two main types of sleep. REM (rapid eye movement) sleep is the one in which you do most of your active dreaming. Non-REM sleep consists of four stages of deeper sleep. Each sleep stage is important, but deep sleep and REM sleep are particularly important.
So why is it so important for us to sleep?
Studies have proven that sleep is necessary for survival. Lack of sleep has been shown to impair the body’s ability to fight infection. If that’s the case, then how can you be sure you’re getting enough sleep?
Most people need about eight hours a night, but some may need more or less than that. The real key is how you feel in the morning. If you feel refreshed and awake, you’re probably getting enough sleep. To consistently meet sleep requirements for both deep sleep and REM sleep, you need to set the stage for good sleep habits.
Although scientists are still learning about basic sleep requirements, one thing is for certain: Not getting enough sleep is hazardous to your health. Insufficient sleep over time has been linked to an increase in body weight, a higher risk of diabetes and heart problems, an inability to recall new information, and an increase risk for depression and substance abuse. So take care of yourself and make sleep a priority.