Comedown or
crashing is the deterioration in
mood that happens as a
psychoactive drug is
cleared from the
blood and thus the
cerebral circulation. The improvement and deterioration of mood (
euphoria and
dysphoria) are represented in the cognitive as high and low
elevations; thus, after the drug has
elevated the mood (a state known as a
high), there follows a period of
coming back down. Such a comedown (
down, low, crash) can happen to anyone as a transient
symptom, but in people who are
dependent on the drug (especially those
addicted to it), it is an early symptom of
withdrawal and thus can be followed by others. Various drug classes, most especially
stimulants and
opioids, are subject to crashing. A milder analogous mood cycle can happen even with
blood sugar levels (thus
sugar highs and
sugar lows), which is especially relevant to people with
diabetes mellitus and to parents and teachers dealing with children's behavior.