Alertness

Lack of alertness is a symptom of a number of conditions, including narcolepsy, attention deficit disorder, chronic fatigue syndrome, depression, Addison's disease, and sleep deprivation.

Research shows that for people "...engaged in attention-intensive and monotonous tasks, retaining a constant level of alertness is rare if not impossible."

If people employed in safety-related or transportation jobs have lapses in alertness, this "may lead to severe consequences in occupations ranging from air traffic control to monitoring of nuclear power plants.

Similarly inhibition or reduction of mechanisms causing sleepiness, or drowsiness such as certain cytokines and adenosine (as with caffeine) may also increase perceived wakefulness and thus alertness.

[3] Many Neurotransmitters are in effect to experience wakefulness to include GABA, Acetylcholine, Adenosine, Serotonin, Norepinephrine, Histamine, and Dopamine.

The stimulant and adenosine receptor antagonist caffeine is widely used to increase alertness or wakefulness and improve mood or performance.

[13] During the Second World War, U.S. soldiers and aviators were given benzedrine, an amphetamine drug, to increase their alertness during long periods on duty.

][citation needed] British troops used 72 million amphetamine tablets in the second world war[14] and the Royal Air Force used so many that "Methedrine won the Battle of Britain" according to one report.

Beyond good sleep, physical activity, and healthy diet, a review suggests odours, music, and extrinsic motivation may increase alertness or decrease mental fatigue.

[2] A study suggests non-genetic determinants of alertness upon waking up from sleep are:[25][26] The baseline of daily alertness[clarification needed] is related to the quality of their[clarification needed] sleep (currently[may be outdated as of July 2023] measured only by self-reported quality), positive emotional state (specifically self-report happiness), and age.