Why we need sleep
Story and Photo by Hudson Lofchie
Published on Jan 19, 2011 in the California Aggie (theaggie.org)
Few things in this world feel better than a full night’s sleep; a night from which you wake up feeling refreshed, energized and clear-headed. The human desire, and requirement, for sleep is so hard-wired that going against nature’s intended sleep patterns can have interesting side effects and debilitating consequences.
College students, the most notorious breakers of sleep-cycles, should take heed of what their bodies are trying to tell them when they are tired. The feelings of exhaustion and fatigue may be curbed temporarily by a cup of coffee, but a quick fix does not address the underlying physiological causes. Using coffee to mask the feelings of exhaustion is like giving a broken, rusted bridge a new coat of paint. It may look good on the outside, but underneath, all the problems still exist.
According to Irwin Feinberg, a professor of psychiatry and behavioral sciences here at UC Davis and a researcher in the UC Davis Sleep Lab, sleep is broken into two distinct phases: the media-popularized REM (Rapid Eye Movement) phase, and the lesser known, nREM (Non Rapid Eye Movement) phase. Ironically, we only spend about 25 percent of our time asleep in the REM phase.
During sleep, we experience cycles of about 90 minutes of nREM, followed by a few minutes of REM. The differences in brain and metabolic function during REM and nREM, measured by electrodes on the head, are quite profound.
Sleep is not just a way to recharge our bodies’ batteries. The REM phase is associated with dreaming, and during REM, the brain is extraordinarily active, using the same amount of oxygen as it does while awake. Feinberg said that dreaming is the process of replaying memories and converting important ones from short-term memory into long term memory. In other words, if you deny your body sufficient REM sleep, your ability to process memory decreases.
Thomas Anders is a retired professor of Psychiatry and Behavioral Sciences and a former researcher at the UC Davis M.I.N.D. Institute. He said that the brain is so active during the REM phase, that it inadvertently activates neural pathways that control muscle movements. The brain automatically paralyzes all peripheral muscles to prevent movement and potential injury during sleep.
NREM is the sleep that we associate with being physically rested. It is a deep, dreamless sleep during which the body recovers from fatigue and repairs cellular damage. During nREM, the brain uses about 25 percent less oxygen than during waking hours.
“Breathing and metabolism are slowed, and the body and brain become very quiet,” Anders said.
Without adequate sleep, you can begin to hallucinate, become disoriented and become very sick as your immune system fails. Death from lack of sleep is a very rare occurrence because usually the body will just spontaneously fall asleep when the need becomes too great. The body’s dependence on sleep is the reason why sleep deprivation is such an effective method of torture.
Certain conditions like narcolepsy and sleepwalking are directly related to irregular sleep functions. Narcolepsy is a genetic disorder that causes the body to involuntarily fall into an REM sleep cycle. When this happens, the body becomes paralyzed and, if walking or driving, there can be serious consequences. Narcoleptics are not allowed to drive because of the potential danger.
Sleepwalking actually occurs during the “deep sleep” nREM phase. It is impossible for the body to move during REM because of the natural paralysis. Anders’ research has shown that sleepwalking can last anywhere from 30 seconds to four or five minutes. The popularized idea that someone can sleepwalk and end up hundreds of miles away is a myth without scientific grounding.
“Much less is known than needs to be known about a state in which we spend a third of our lives,” Feinberg said.
Sleep is still a frontier of science, and more is discovered every day about how it works. Evolution has had millions of years to build a sleep cycle that works for us.
Note to inhabitants of the 24-hour study room: you’ll get more out of studying by going to sleep rather than pulling an all-nighter.