Special emphasis was placed on distinguishing between states of human health and disease that are connected to changes in temporal organization, and a conceptual classification was suggested for these situations. Selected abbreviations and acronyms A amplitude CRT choice reaction time DH dominant hand L:D Iight/dark M mean NDH nondominant hand Φ acrophase Inhibitors,research,lifescience,medical (peak time) PS paradoxical sleep REM rapid eye movement RT reaction time

SCN suprachiasmatic nucleus SD Sprague-Dawley (rat) SRT single reaction time τ period
Forty million Americans are afflicted with chronic disorders of sleep and wakefulness, which interfere with work, driving, and social activities. Sleep disorders cause 38 000 cardiovascular deaths and cost over 16 billion annually.1 Indirect costs of accidents, property destruction, litigation, hospitalization, and death add another 50 to $100 billion.1 The most common

sleep disorders include insomnia, sleep apnea, restless legs syndrome, and narcolepsy.1-3 Classification of sleep disorders Inhibitors,research,lifescience,medical The International Classification of Sleep Disorders diagnostic and coding manual 2000 lists four major categories of sleep disorders: dyssomnias; parasomnias; sleep Inhibitors,research,lifescience,medical disorders associated with mental, neurologic, or other medical disorders; and proposed sleep disorders (Table I) 4-7 Table I Classification of sleep disorders4. NOS, not otherwise specified; REM, rapid eye movement. Dyssomnias are disorders characterized by either excessive sleepiness Inhibitors,research,lifescience,medical or difficulty initiating or maintaining find more sleep4. On the basis of pathophysiological mechanisms, they can be subdivided into intrinsic, extrinsic, and circadian rhythm sleep disorders.4-9 Intrinsic sleep disorders are disorders that originate or develop within the body or that arise from causes within the body Common intrinsic sleep disorders include idiopathic and psychophysiological insomnia, narcolepsy, obstructive sleep apnea syndrome (OSAS), periodic limb movement disorder (PLMD), and restless legs syndrome (RLS)4-7. Sleep disorders caused Inhibitors,research,lifescience,medical by external factors are termed extrinsic sleep disorders and include inadequate sleep hygiene,

environmental sleep disorder, adjustment sleep disorder, insufficient Phosphoprotein phosphatase sleep syndrome, limit-setting sleep disorder, sleep-onset association disorder, and hypnotic-, stimulant-, or alcohol-dependent sleep disorder:4-7 Circadian rhythm sleep disorders share a common chronophysiological basis whereby there is a discordance between the patient’s sleep pattern and the desired or societal sleep norm.4-9 Examples of circadian rhythm sleep disorders include shift work sleep disorder, delayed sleep phase syndrome, and advanced sleep phase syndrome. Parasomnias are characterized by undesirable behavioral and physical phenomena that occur predominantly during sleep4-7. They include disorders of arousal, partial arousal, and sleep-stage transition.