one of the original constitutional body types based on the four humors associated with Hippocrates (c. 460–c. 377 bce) and described by Galen, who attributed the apathetic character of the phlegmatic type to the dominance of phlegma, or mucus, over other body fluids, or humors. See Carus typology; humoral theory.
one of four basic types of sleep disorders, differentiated from the other types in that it results from a mismatch between one’s internal circadian rhythm and one’s actual sleep schedule. The equivalent classification in DSM–IV–TR is circadian rhythm sleep disorder (or in DSM–5, circadian rhythm sleep–wake disorder). Rotating work-shift schedules and jet lag are two common causes of this disorder. Diagnosis can involve observation in a sleep laboratory, in which such criteria as nocturnal awakening, sleep time, sleep efficiency, breathing patterns, body temperature, minutes of REM sleep, and sleep latency are measured.