sleep Why is sleep so critical to our well-being? If resting in bed were all it took to recharge body and mind for the coming day, insomniacs could take in their favorite late night television and start the next day fresh. But surprisingly, it's not how much sleep you get that's important—it's the level of sleep you achieve that truly restores you, body and mind.

Sleep can be divided into two crucial phases:

  • Non-rapid eye movement (NREM) sleep takes up about 75% of the average sleeper's night. The earliest phase of NREM sleep begins with general relaxation of muscles. This relaxed state eventually culminates in the deepest sleep level when it appears that protein synthesis, growth hormones, immune function, and the mind are given a boost. Delta waves—the slowest and largest waves—signal the onset of this most rejuvenating sleep level.
  • Rapid eye movement (REM) sleep takes up about 25% of an average dreamer's night. Dreams that occur during REM sleep might provide, in a sense, a sorting through of free-floating information. REM sleep is thought to be a very important period for mental revitalization.

In addition to productivity and safety consequences, research shows that people who have insomnia or are chronically sleep deprived may be more likely to have an increased risk of:

People who do not get enough sleep may also:

  • Have behavioral problems
  • Drink more alcohol and use more sedatives than they usually do
  • Experience a decreased enjoyment in life