Table 1.

Sleep disorders, their general symptoms, and changes in sleep architecture.

Sleep Disorders			Sleep Architectural Changes	General Symptoms
1.	Insomnia	(a)Primary Insomnia Some intrinsic/extrinsic factors or both are associated with its etiology	Both NREM and REM sleep	•Repeated sleep-initiation difficulties, Decreased sleep duration •Reduced sleep consolidation, or quality even though the patients get adequate time and opportunity to sleep •Insomniac patients may tend to wake-up early and no signs of restorative sleep
		(b)Secondary insomnia As consequences of a medical or psychiatric illness, another sleep disorder, or substance abuse
2.	Hypersomnia	(a) Kleine-Levin syndrome	Both NREM and REM sleep	•Primarily excessive daytime sleepiness •Nocturnal sleep remains normal •Behaviorally chosen nocturnal sleep restriction to perform activities such as job, study, watching TV, etc
		(b) Menstrual-related hypersomnia
		(c)Idiopathic hypersomnia
		(d)Behaviorally Induced Insufficient Sleep Syndrome (BIISS) or Insufficient sleep syndrome
3.	Parasomnia	1.Disorders of arousal from NREM Sleep	Both NREM and REM sleep	•Sleep state accompanied by some physical or emotional sporadic events, such as abnormal sleep-related movements, emotional and behavioral incitement, intense dreaming, etc. •These disorders may emerge from either NREM or REM sleep •Some of the parasomnias may appear due to drug or substance abuse or medical conditions •In sleep-related eating disorders (SRED), patients exhibit recurring episodes of eating during the transition from sleep to arousal
		(a)Confusional arousals (b)Sleepwalking (c)Sleep terrors
		2.Parasomnias associated with REM sleep	Mostly REM sleep
		(a)Rapid eye movement sleep behavior disorder (RBD) (b)Recurrent isolated sleep paralysis (c)Nightmare disorder
		Other Parasomnias	Mostly REM sleep
		(a)Sleep-related dissociative disorders (b)Sleep enuresis (c)Sleep-related groaning (d)Exploding head syndrome (e)Sleep-related hallucinations (f)Sleep-related eating disorder
4.	Narcolepsy		REM sleep	•Associated with excessive daytime sleepiness •Hypersomnia is the most common symptom of narcolepsy •Sleep attacks occur despite having sufficient nocturnal sleep •Daytime sleep occurs daily, recurring typically every 2 hours (can vary) •Cataplexy is defined as sudden and transient episodes (< 2 minutes) of loss of muscle tone •It is generally bilateral and triggered by emotions (usually laughing and joking)
	A.Narcolepsy with cataplexy B.Narcolepsy without cataplexy
5.	Circadian Rhythm Disorders		Both NREM and REM sleep	•The sleep-wake cycle is misaligned with circadian timing •The patients complain of either insomnia or excessive sleepiness
	A.Advanced sleep-phase syndrome B.Delayed sleep-phase syndrome
6.	Sleep Apnea		Both NREM and REM sleep	•The upper airway pathway is obstructed, which causes increased effort in breathing and inadequate ventilation during sleep •In central sleep apnea, respiration is altogether stopped intermittently or cyclically during sleep because of dysfunction in neural circuitries of the central nervous system
	A.Obstructive Sleep Apnea B.Central Sleep Apnea
7.	Restless Leg Syndrome / Periodic Limb Movement Disorder		Both NREM and REM sleep	•A very painful sensorimotor neurological sleep-associated disorder •The subjects feel an extreme urge to move extremities, mostly the legs, during sleep as the subjects feel unpleasant sensations or pain in the affected limbs •The periodicities of leg movement increase by evening and worsen during sleep