Sleep has great general biological significance, playing an important role in the function of the brain. During sleep, metabolic rates and muscle tone decrease, contributing to the restoration of physical and psychological resources. Due to the most common sleep disorder — insomnia, there is great exposure to heart diseases such as myocardial infarction and stroke. It negatively affects the learning processes, short-term and long-term memory. This condition can cause mental disorders, leg cramps, and abnormal heart rhythms. This disorder increases the level of blood sugar, chronic fatigue.
The sleep period consists of two phases: non-REM and REM, or rapid eye movement. During REM sleep, the brain filters the information received per day, discarding unnecessary data. Hippocampus, facilitating long-term memory consolidation, is associated with non-REM sleep. A study shows that the REM phase erases some amount of data (Li, Ma, Yang, & Gan, 2017). Neurons in the hypothalamus, also known for producing hormones stimulating appetite, are responsible for this cleansing. One of REM sleep characteristic features is a vivid dream when the brain recalls the period of wakefulness. Dreams are related to one’s actual experiences as an individual and are a significant part of people’s consciousness. People solve some difficult tasks in a dream, make a breakthrough into a new field of knowledge, and generate brilliant ideas.
REM sleep is especially crucial for newborns, providing nerve stimulation that promotes the general development of the nervous system. Different stages of life correspond to varying amounts of sleep. A newborn might spend about 50% in the REM phase, while at the age of two, this phase takes about 25% from the whole sleep period (Li, Ma, Yang, & Gan, 2017). Teenagers sleep longer, and older people need more time to fall asleep. The reason for these changes lies in the fact that sleep has a different purpose at different stages of life. In youth, it plays a vital role in brain maturation; in old age, it is necessary to prevent degenerative conditions.
Reference
Li, W., Ma, L., Yang, G., & Gan, W. B. (2017). REM sleep selectively prunes and maintains new synapses in development and learning. Nature Neuroscience, 20(3), 427-437.