Sleep medicine

condition of not having enough sleep

Polysomnography (PSG) is a multi-parameter type of sleep study and a diagnostic tool in sleep medicine. The test result is called a polysomnogram, also abbreviated PSG. The name is derived from Greek and Latin roots: the Greek πολύς (polus for "many, much", indicating many channels), the Latin somnus ("sleep"), and the Greek γράφειν (graphein, "to write").

medical specialty or subspecialty devoted to the diagnosis and therapy of sleep disturbances and disorders

cumulative effect of not getting enough sleep

drink taken shortly before bedtime

quantitative measure of the tendency to fall asleep

rare sleep pattern whereby the sleep schedule of a person shifts later every day

psychiatric treatment

thumb|upright=1.3|alt=Example hypnogram for a normal, healthy adult. Within the first hour of sleep SWS is displayed. Cycles of REM and NREM sleep proceed. During the third cycle of sleep there are two brief wake states. During the second half of the sleep period more REM sleep is displayed and there is little SWS detected.|Example hypnogram of a normal, healthy adult Here, both stage 3 and stage 4 are shown; these are often combined as stage 3.