Monday, July 25, 2011

Exercise Leads to a Deeper Sleep

Exercise promotes the most rejuvenating component of sleep. Slow-wave sleep, also called Stage 3 sleep or delta sleep is the deepest stage of sleep from which it's hard to rouse an individual. We call this sleep "slow-wave sleep" because when we measure the brainwaves, quite literally the frequency of the waves is very slow, and the waves are very tall and deep.

While we don't always know why, slow-wave sleep is the special component of sleep. It is what gives us a sense of feeling restored in the morning and when we miss this sleep, we feel this in our joints and muscles – that familiar flu-like feeling of just not having had enough sleep.

In a recent study,athletes were exposed to a noise stimulus, not loud enough to wake the subject but enough to produce an interruption in the electronic architecture of their sleep. The changes in sleep architecture are measured by looking at brainwaves. We call these events EEG arousals: the person doesn't wake up but his or her brainwaves change. Anything can cause these events – snoring, a crying baby, pain, the sound of a telephone, even heartburn. In the study non-athletes (people who were identical in every way except for the fact they were not intense, habitual runners) were exposed to the same noise stimulus.

The researchers found that the athletes, despite being exposed to stimuli that clearly interrupted their sleep (as measured by changes in their brainwaves) woke up feeling refreshed. On the other hand, the average person who did not exercise in the same way woke up feeling terrible even though they were exposed to the same noise. What accounts for the difference? One reason may be that the athletes had more slow-wave sleep and this was somehow protective and resulted in a feeling of restoration in the morning.

Another benefit of exercise concerns its ability to speed up our metabolism and in the process elevate the body temperature deep in our core. We burn a lot of energy while engaged in exercise, even if we are just walking briskly and this energy generates heat. It takes the body hours to cool down by tiny degrees in order to return to our resting baseline. This cooling of our body temperature invites sleep.
This means that if you exercise at the right time you can fall asleep faster. The important thing is to make sure not to exercise too close to bedtime. If we do, it takes too long for the body's temperature to cool down and sleep actually takes longer to arrive. Plus we feel too energized to feel sleepy.

Our lives are more hectic than ever and to keep up and stay healthy we need to spend more time in slow-wave sleep. Finally, a growing number of innovative tools are available that can help measure, monitor and improve our sleep. Some of them even make sleep more fun.

Source: USA Today 7/22/11

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