In mammals and birds sleep is divided into two broad stages..
NREM or non-REM (Non rapid eye movement)
REM stage (rapid eye movement)
NREM sleep stage (non rapid eye movement)
NREM consists of three stages. There is relatively little dreaming in NREM.
Stage N1 Refers to the transition of the brain from alpha to theta waves, this is the state when you start to feel drowsy. this also is when the body gets sudden twitching or muscular spasms known as hypnic jerks and at this N1 stage you also loose most of your conscious awareness of the external environment around you.
Stage N2 Muscular activity now decreases (no jerking) and conscious awareness of the external environment decreases to the point of no conscious awareness of the outside world.
This stage occupies 45–55% of total normal sleep in adults.
Stage N3 This is deep or slow wave sleep known as "delta wave sleep" this is characterized by big slow delta waves in the brain activity.
REN sleep stage (rapid eye movement)
Rapid eye movement sleep, or REM sleep stage accounts for 20–25% of total sleep time in most adults. and is characterized by the rapid movement of the eyes under the eyelid.
This is also the stage of our most memorable dreams.
Science believes the low level physical activity aspect of REN sleep induced by chemicals released in the brain comes from our distant past when our ancestors lived in trees to avoid falling or causing physical hurt to themselves whilst acting out their sometimes vivid dreams when asleep.
Sleep is a naturally recurring behavioral state characterized by little physical activity with almost no awareness of the outside physical world.
Sleep allows your body to physically repair itself after the ware and tear of the day.
A sleep disorder is a medical disorder causing characteristic disruptions to sleep patterns of a person.
Normal sleep is characterized by little or low physical activity with no disruptions to sleep patterns and almost no awareness of the outside world.
Some sleep disorders are serious enough to interfere with normal physical, mental and emotional functioning and can cause body fatigue which can lead the individuals immune system to malfunction.
Disruptions in sleep may be caused by a variety of issues, from nightmares to teeth grinding. When a person suffers from difficulty in sleeping with no obvious cause, it is referred to as insomnia other sleep disorders may also cause sufferers to sleep excessively, a condition known as hypersomnia. Management of sleep disturbances can greatly improve your wellbeing.
Types of sleep disorder.
Insomnia ..the most common type of sleep disorder.
Sleep apnea .. breathing temporarily stops during sleep due to narrowing of the upper airways. These pauses in breathing interrupt your sleep, leading to many awakenings from your sleep cycle each hour. Sleep apnea is considered to be a potentially life-threatening condition that requires immediate medical attention.
Restless legs syndrome or RLS ..a cruel, irresistible and involuntary urge to move your arm and leg muscles, even whole body jerks are not uncommon..
people suffer from RLS just as they are trying to get to sleep, the irony of this is the more sleepy and under your brain gets and just as you are going to sleep (typically in the N1 stage) The urge to move your limbs becomes unbearable and in a lot of cases involuntary.
Narcolepsy ..is a sleep disorder that involves excessive, uncontrollable daytime sleepiness
Sleep disorders are classified into two kinds
Primary sleep disorders or Dyssomnias are chronic disturbances in the quantity or quality of sleep that interfere with a person's ability to function normally. examples of ailments in this category are primary insomnia, hypersomnia, narcolepsy, breathing-related sleep disorder and circadian rhythm sleep disorder
Parasomnias, which are the second category of sleep disorders, include those in which people experience physical events while they are sleeping. Disorders in this category include nightmares, sleep terrors, sleepwalking and parasomnia.
Hypersomnia is a condition marked by excessive sleepiness during normal waking hours. even though he or she is sleeping normally at night. People who have hypersomnia can fall asleep at any time: for instance, at work or while driving. An adult is considered to have hypersomnia if he or she sleeps regularly for more than 10 hours day.
Memory lapses of loss of memory.
Impaired immune system.
Symptoms similar to ADHD.
Increased heart rate.
Risk of type 2 diabetes.
Risk of heart disease.
Decreased reaction time and accuracy.
Decreased body temperature.