Sleep

Sleep; Physiology and stages
Sleep impacts all of the body’s major physiologic systems, including thermoregulatory, musculoskeletal, endocrine, respiratory, cardiovascular, gastrointestinal, and immune systems. Sleep also impacts human’s weight, mental health, and overall quality of life. Incomplete or add up to absence of sleep, bothered sleep, and low quality sleep would all be able to affect his physical, mental, and emotional health.
Physiology of sleep:
1- Thermoregulatory:
Our body temperature is higher during the day and lower during the evening. In ordinary sleepers and typical conditions, sleep beginning happens as a person’s body temperature falls and his heat loss increase, these progressions additionally incite the maintenance of sleep.
2- Musculoskeletal:
Physiologically, most muscles relax during non-rapid eye movement (NREM) sleep, and become exhibiting a lack of muscle tone similar to paralysis during rapid eye movement (REM) sleep, except for the ocular muscles and the diaphragm.
3- Endocrine System:
The endocrine system has a complicated response to sleep. The secretion of a few hormones increases during sleep (e.g., growth hormone, prolactin, and luteinizing hormone), while the secretion of different hormones is inhibited (e.g., thyroid stimulating hormone and cortisol ).

4- Respiratory System:
Sleep has an enormous effect on the respiratory system, and vice versa. Ventilation and respiration both change while a person sleeps. In particular, they turn out to be speedier and more changeable during rapid eye movement (REM) sleep. The cough reflex is also suppressed during REM and NREM sleep.
5- Cardiovascular system:
Blood pressure and heart rate both change during sleep. There are fleeting increases in the person’s blood pressure and heart rate during sleep awakening, and large body movements. In the couple of hours before a person wakes up, and as the person wakes up in the morning, there is an increase in both heart rate and blood pressure. Lack of sleep and disordered sleep are also connected with heart attacks and possibly stroke.
6¬- Gastrointestinal System :
Gastrointestinal reflux disease (GERD) is a typical disease in which the stomach substances of food and acid back up into the esophagus and disrupt the person’s sleep. people who experience nighttime GERD will probably have sleep issues like insomnia, obstructive sleep apnea (stop breathing briefly), drowsiness and dizziness, and restless legs syndrome, compared to people without nighttime GERD.
7- Immune system:
Sleep disorders are a challenge to the proper functioning of the body’s protection systems , especially sleep loss. Both total sleep time (TST) and slow-wave sleep (SWS) rise during intense infection. Conversely, severe illnesses, discomfort, and pain can inhibit SWS and, therefore, slow down healing.
Stages of sleep:
There are five stages of sleep. Stages 1-4 are non-REM sleep, followed by REM sleep.
– Stage 1 is a light sleep where you drift in and out of sleep and can be simply awakened. In this stage, the eyes move slowly and muscle activity slows. During this stage, a lot of people encounter sudden muscle contractions preceded by a feeling of falling

– In stage 2, eye movement stops and brain waves become slower. The body begins to prepare to get into deep sleep, as the body temperature begins to become less and the heart rate slows.
– When a person moves into stage 3, intensely slow brain waves called delta waves are interspersed with smaller, quicker waves. This is deep sleep. It is during this stage that a person may undergo sleepwalking, night terrors, talking during sleep, and bedwetting. These symptoms are known as parasomnias, and tend to occur during the transitions between non-REM and REM sleep.
– In stage 4, deep sleep continues as the brain produces delta waves . People awaken from this state feel disoriented for a few minutes
– During stage 5 :REM (rapid eye movement) sleep, the eyes stay closed but move quickly from side-to-side, maybe associated with the intense dream and brain activity that occurs during this stage.