How much sleep do you need?

Most of us don’t give much thought to how much sleep we need. It’s generally what we do when we feel tired. You might be surprised to know that there are complex mechanisms in your body that control when you’re awake, and change when you’re asleep.

In adults the most natural cycles of being awake and asleep are 16 hours of activity, followed by 8 hours of sleep. These cycles of being awake and sleeping are controlled by several internal systems, that include the Biological Sleep Clock located in the brain, our internal Sleep Wake Meter, our Body Thermometer, and our Sleep Monitor

Our Biological Clock regulates body temperature, hormone levels and sleep patterns. Because our Biological Clock is triggered by sunlight and darkness, and the fact that the desire to sleep is generally strongest between midnight and 6 AM, shift work, time zone travel and staying up later than usual, can interfere with our sleep patterns.

Our Sleep Wake Meter determines how much sleep the body needs. While awake the body produces a compound known as adenosine. The longer you’re awake, the more adenosine your body produces. As you sleep the body breaks down adenosine. If you don’t get enough sleep, eventually you’ll have to sleep longer for your body to eliminate excess adenosine. So getting less sleep than you need, will catch up to you.

Body temperature is another system that changes as we sleep. Body temperature falls during the first part of the sleep cycle. Body temperature reaches it’s lowest point around 5 AM, and then starts to rise, enhancing alertness.

Our Sleep Monitor identifies the stage of sleep we’re in. Electrical impulses from the brain and the muscles around the eyes and limbs form characteristic patterns. These monitors represent internal controls that allow us to sleep at night, and be awake and alert during the day. When these systems are out of balance, our ability to have a good night’s sleep becomes impaired.

There are two main stages of sleep. The first is “NREM (non-rapid eye movement)” or “Quiet” sleep. During this stage of sleep blood supply to the muscles is increased, energy is restored, tissue growth and repair occur, and important hormones are released for growth and development.

The second stage of sleep is called “REM (rapid eye movement)” or “Active” sleep. During this stage of sleep our brains are active, dreaming occurs, our bodies become immobile, and breathing and heart rates irregular. Clinical research has proven that the more time you spend in this stage of sleep without interruption, the more rested you feel on waking. REM sleep is important for the brain to help learning, thinking and organizing information. REM sleep is easily interrupted by sleep partners, unusual noises, lighting conditions and physical discomfort (pressure against pressure points that causes tossing and turning).

Okay ... you’ve heard the scientific reasoning ... now how much sleep do you need?

Research suggests that newborns typically need 16 to 18 hours, preschool children need 10 to 12 hours, school aged children need 10 to 11 hours, teenagers need 8½ to 9½ hours, and adults need 7 to 9 hours of sleep a night.

The Biological Clock in teenagers often tells them that the natural time to fall asleep is 11 PM or later. Unfortunately, if they have to get up at 6:30 AM to get ready for school, they don’t get enough sleep. That’s why they often sleep longer on weekends. It’s catch up time.

As we age we have fewer problems falling asleep, but health, body changes, and decreased activity can affect our quality of sleep. Unlike teenagers, our Biological Clock is generally advanced, making us feel tired as early as 8 PM. Deep sleep stages become shorter or diminish, but our need to sleep does not.

During our entire adult life we continue to need 7 to 9 hours of sleep a night. One mistake many of us make, is taking naps during the day. When our body temperature drops during the day, we often tend to nap. Although these naps tend to satisfy some of our need to sleep, this can end up keeping us awake at night. To nap or not to nap, that’s the question. If the goal is to sleep longer and better at night, napping may not be a great idea. On the other hand, to improve short term alertness, a 15 to 20 minute nap is a great idea, especially when driving long distances.

When it comes to learning, sleep is food for the brain. Studies show that those that sleep 8 hours a night or more, outperform those that sleep 7 hours or less. Lack of sleep causes thinking processes to slow down, making it harder to focus and pay attention, and leads to faulty decision making and greater risk taking. A lack of sleep slows down reaction time, which is significant to driving. When people that lack sleep are tested using a driving simulator, they perform just as poorly as people who are drunk. The bottom line is not getting a good night’s sleep can be downright dangerous.

Night shift workers often find themselves drowsy at work, and have difficulty falling and staying asleep during daylight hours. Night shift workers are more likely to have physical problems such as heart disease, digestive disturbances, infertility and emotional problems. Night shift workers are also at greater risk of being in car crashes, as they drive home from work. The loss of just one hour of sleep during the change of time for Daylight Savings causes a 7% increase in traffic accidents that day, according to a survey reported in USA today. Last but not least, major industrial accidents like Three Mile Island, Chernobyl and the Exxon Valdez Oil Spill, were caused in part by mistakes by overly tired workers.

Although you may put off sleep in order to squeeze more into your day, eventually you will have to sleep. So why not get the sleep you need without fighting it? A GOOD night’s sleep can be just what you need to make sure you have a GOOD day.

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