communicate with him or her, and can be  awakened only with great difficulty.
somnolence (or “drowsiness”) A state of near-sleep, a strong  desire for sleep, or sleep-
ing for unusually long periods. It has two di stinct meanings, referring both to the usual
state preceding falling asleep and to the chro nic condition that involves being in that
state independent of a circadian rhythm. Compare with HYPERSOMNIA .
specific food cravings Irresistible desire for sp ecial types of food.
startle response (or “startle reaction”) An involuntary (reflexive) reaction to a sudden
unexpected stimulus, such as a loud noise or sharp movement.
stereotypies, stereotyped behaviors/movements Repetitive, abnorma lly frequent, non-
goal-directed movements, seemingly driven , and nonfunctional motor behavior (e.g.,
hand shaking or waving, body rock ing, head banging, self-biting).
stress The pattern of specific and nonspecifi c responses a person makes to stimulus
events that disturb his or he r equilibrium and tax or exceed  his or her ability to cope.
stressor Any emotional, physical, social, economic, or other factor that disrupts the nor-
mal physiological, cognitive, emotional, or  behavioral balance of an individual.
stressor, psychological Any life event or life change that may be associated temporally
(and perhaps causally) with the onset, occurr ence, or exacerbation of a mental disorder.
stupor Lack of psychomotor activity , which may range from not actively relating to the
environment to complete immobility.
submissiveness Adaptation of one’s behavior to the actual or perceived interests and
desires of others even when doing so is antithetical to one’s own interests, needs, or