heat effects
changes in mental or physical conditions due to perceived or actual ambient temperatures above the normal comfort range. Perceived heat may be affected by humidity or individual cognitive factors; high humidity usually makes excessive heat less tolerable. The main physiological heat effects are heat-induced asthenia, heatstroke, heat exhaustion, and severe circulatory disorders (e.g., heart attacks) caused by excessive demands on the cardiovascular system to circulate blood near external surfaces for a cooling effect. Because of variable perceived heat effects, studies of psychological effects are less conclusive, although performance appears to improve with increasing ambient temperatures up to a level of around 32°C (90°F), after which arousal and performance decline. High temperatures can have adverse effects on feelings and emotions and can influence aggression, although no consensus exists in the scientific literature on the
exact degree of this influence. Some researchers believe that aggression increases with temperature in a linear manner, whereas others hold that beyond a certain temperature, the desire for escape or relief from the heat supersedes the tendency toward aggression. See acclimatization; overheating.