What happens when we sleep
Sleep is a natural state of altered states of consciousness that are in a person’s life alternates with the state of wakefulness. The stages of wakefulness and sleep are exchanged properly and cyclic and represent one of the important biological rhythms. Is determined as a condition of the function of the nervous system. State of relative rest of the body where absent response to most stimuli from the environment, reduced the activity of skeletal muscle was reduced and a number of autonomic functions (pulse, blood pressure, body temperature, respiration).
During sleep, the majority of systems are in an anabolic state (construction of the immune, nervous and muscular system and skeleton). Mental activity is also reduced and significantly altered. It occurs in the form of occasional dreams. Known feature of sleep in humans is a dream. An experience that closely resembles waking life while in progress and that is usually later may vary as a fantasy. No sleep is generally not good for human health, especially for people with physical illnesses. The recommended duration of sleep is about 8 hours.
Our sleep is divided into 90 minute cycle. The first two dominate deep sleep while the brain is mostly inactive, there after are alternating REM (rapid eye movement) and non-REM. Emotional responses during non-REM are more positive compared to reactions in the REM stage. Normal asleep is through the non-REM phase. It is thought that people who have problems with depression and negative emotions go immediately into REM. Then, they stay too long in it, which is not good for mental health. People can suffer from a number of disorders.
This includes:
- dyssomnia (such as insomnia, hypersomnia and sleep apnea)
- parasomnia (such as somnolence and REM behavior disorder)
- bruxism and circadian rhythm sleep disorder
There are four stages of non-REM. Starts with phase called synchronized sleep. This phase has four sub-phases:
– Phase 1 – (first 10 minutes), the activity is out of synchronization, alternate fast waves, alpha (8 – 12 Hertz) and theta waves (3.5 – 7.5 Hertz)
– Phase 2 – (takes 15 min.), theta waves with K-complexes (one extremely negative and extreme positive deflection), and sleep spindles, salve waves (12 – 14 Hz) that occur 2 to 5 times per minute. K-complexes and sleep spindles as a result of brain mechanisms that reduce the sensitivity of the surrounding stimuli.
– Phase 3 – (in 20 – 50% of the time), delta waves (small frequency and high amplitude).
– Phase 4 – delta waves in more than 50% of the time (45 min).
The slow-wave sleep (SWS) are stages 3 and 4. In the slow waves of neural activity is highly synchronized. Rhythm breathing and heart rate is slower in each next stage of sleep than in the previous phase and increases the percentage of slow waves during large amplitude non-REM sleep. Across the stages 3 and 2 exceed in the first REM phase, after 90 minutes of beginning sleep. This leads to rapid eye movement, or active sleep, making this phase was named.
In REM, brain wave activity is very big. There are alpha waves that occur in the waking state and other physical activities are intensified and it often dream. Phase becomes longer and up to half an hour, eyes sleeper run to the left and right behind closed eyelids intensity of 50 to 60 times a minute, which is an indicator of excessive activity of the nervous system, also increases your heart rate, faster breathing, blood pressure rises and there are tugs and muscle cramps.
After REM everything is repeated at intervals of about 90 minutes. Earlier in the night predominant phases are 3 and 4, toward the morning phase 4 is lost, phase 3 will be shorter and extends the REM phase. The physiological component of dreaming is expressed in REM phase. When a person falls asleep external stimuli can stop the dream, as such as noise in the 3rd phase can cause restore to the second phase, a slow or stop. Fear may arise in the 4th stage of non-REM, like walking in a dream. It is a distinct sense of fear in which the person often wakes up screaming. This should be distinguished from nightmares (extremely unpleasant dream) in REM sleep.