Sleep disorders are classified as follows:
- Insomnia: It has been typically found nearly in all age groups. Insomnia is usually considered to be either acute or chronic. Insomnia becomes chronic if having trouble falling asleep or staying asleep at least three nights per week for three months or longer. Insomnia mainly includes:
- Psychophysiological insomnia is one of the most common types of insomnia. A patient with psychophysiological insomnia focuses on their sleep, and worries about not getting enough which make it more difficult to treat.
- Paradoxical insomnia is characterized by complaints of little or lack of sleep over long periods of time without the level of impairment expected with such a level of sleep deprivation. After conducting a sleep lab or polysomnography, the result usually reveals that patient can actually sleep with decreased sleep depth, resulting in morning weakness or fatigue which is generally perceived as lack of sleep.
- Insufficient sleep syndrome: Insufficient sleep syndrome, also known as sleep deprivation and inadequate sleep, is a behavioral induced sleep disorder in which the sufferer simply fails to make adequate time for sufficient sleep. It has been increasingly happening in teenagers from the overuse of internet and smartphones. This sleep insufficiency leads to non-restorative sleep that results in morning weakness which profoundly affects the learning ability.
- Central Origin of Hypersomnolence: Hypersomnias of central origin are a rare cause of excessive daytime sleepiness. It is typically caused by the abnormality of neurological system. The definite diagnosis is highly required to identify whether hypersomnolence is not generated due to lack of sufficient sleep (insufficient sleep syndrome)
- Circadian Rhythm Disorder
- Advanced sleep phase disorder: It is a condition that is characterized by a recurrent pattern of early evening sleepiness and early morning awakening. Nocturnal awakenings might be also found in some cases.
- Delayed sleep phase disorder: It is a disorder in which a person’s sleep is delayed by 2 or more hours beyond the socially acceptable or conventional bedtime. This delay in falling asleep causes difficulty in waking up at the desired time especially in early morning.
- Irregular sleep – wake rhythm: This is a rare form of circadian rhythm sleep disorder, described by numerous naps throughout the 24-hour period, no main nighttime sleep episode and irregularity from day to day. It is usually found in patients with neurodegenerative disorders.
- Non 24 hour sleep –wake disorder (free running): It is a circadian rhythm sleep disorder in which an individual’s biological clock fails to synchronize to a 24-hour day. Most of patients are blind people especially in total blindness cases.
- Jet lag disorder: Jet lag is a temporary disorder that causes fatigue, insomnia and other symptoms as a result of air travel across time zones. It is caused by a disruption of the internal body clock. Symptoms normally improve after resting.