Acupuncture and Hormone Balance
Chapter 4: Melatonin and Sleep
According to a report form the 2002 edition of Brain Facts, a journal published by the Society for Neuroscience, sleep disorders affect up to 70 million people in the United States and cost about $100 billion each year in accidents, medical bills, and loss of work.
How do we sleep?
Sleep follows a regular cycle each night. There are two basic forms of sleep: rapid eye movement (REM) sleep and non-REM (NREM) sleep. Infants spend about 50% of their sleep time in NREM and 50% in REM sleep. Adults spend about 20% of their sleep time in REM and 80% in NREM sleep. Elderly people spend less than 15 % of their sleep time in REM sleep. There is a large variation in total sleep time and the percentage of REM and NREM sleep among individuals
NREM sleep can be divided into 4 stages (stages 1, 2, 3, and 4) each with different brain electrical activity patterns. Stages 3 and 4 are called slow wave sleep (SWS), or deep sleep, during which the brain has fewer activities. Research has show dramatic decreases in blood flow to certain areas of brain during deep sleep as compared to blood flow during wakefulness.
While we are asleep, our brains are on a bit of a "roller coaster ride" through different stages of sleep. As we drift off to sleep, we enter stage 1 sleep. After a few minutes, we enter stage2 sleep, and then stage 3, and then stage 4. Next, it's back up the steps again: stage 3, stage 2 , and followed by a period of REM sleep. The cycle then resumes. During an 8-hour period of sleep, the brain cycles through these stages about 4-5 times, which means we go through one cycle every 2 hours.
During REM sleep, our eyes move quickly, our breath becomes irregular and accelerated, our blood pressure rises, and our muscles lose their tone (paralysis);our brain remains highly active, however. The electrical activity in the brain during REM sleep is similar to that recorded during wakefulness. REM sleep is usually associated with dreams. Often when people wake up from REM sleep, they will say that they were just dreaming. The inactivity of our muscles during REM sleep prevents us from acting out our dreams. REM sleep is important for memory and learning.
Serotonin, a neurotransmitter, can influence both types of sleep. If people are depressed and lack serotonin, they may have much REM sleep and shorter periods of deep sleep. Consequently, they wake up feeling physically and mentally tired rather than refreshed. ON the other hand, too much serotonin can inhibit REM sleep. Another neurotransmitter also regulates the sleep cycle: acetylcholine levels are high during waking and REM stages and low during slow wave sleep periods. Dr. Anne E. Power of the University of California at Irvine suggests that acetylcholine regulates the flow of information between the hippocampus and the neocortex, which is important for effective long-term memory consolidation. Any medication influencing actylcholine levels may potentially interrupt REM and SWS sleep...