Sleep is essential for maintaining a healthy life. The amount of sleep each person needs varies from person to person. The National Institute of Neurological Disorders and Stroke (NINDS) notes that most adults need between seven and eight hours each night. But the number of hours can change based on certain circumstances. For example, during the first three months of pregnancy, women need more sleep.
When people sleep, they go through five stages of sleep: stages one, two, three, four and rapid eye movement (REM). The first four stages of sleep are often referred to as non-REM sleep. The NINDS notes that during a typical night's sleep, people spend 50 percent of the night in stage two sleep, 30 percent of the night in stages one, three and four, and 20 percent in REM sleep.
When people do not get enough sleep or one of the stages of sleep become disrupted, people can suffer from sleep deprivation, which can cause problems during waking hours. For example, after not getting enough sleep during the night, do you have problems getting your work done the next day? People can experience impaired judgment and reaction time. Memory and physical performance can also become affected. If sleep deprivation continues, people can suffer from mood swings and hallucinations, where they perceive things that do not exist.
The NINDS points out that while scientists are still studying all of the effects of sleep, studies done with animals have shown that sleep is needed to survive. In a new study published in Neuroscience, HealthDay News reports that researchers found that sleep also replenishes the brain's energy levels, which help with normal functioning during the day. The study used rats, which the researchers observed during sleep and waking hours.
The researchers focused on the levels of adenosine triphosphate (ATP), a source of energy for cells in the brain. They found when the rats were asleep, the levels of ATP increased in regions of the brain that were active when the rates were awake. This increase of ATP occurred when the rats were in non-REM sleep and those regions of the brain had decreased activity. When the rats were awake, the levels of ATP were steady. The researchers also noted that ATP levels did not increase when rats stayed awake three to six hours later. Since the ATP levels increase in areas of the brain used during waking hours, the researchers hypothesize that sleep gives the brain an energy boost need for normal functioning.