Second wind (sleep)

), a colloquial name for the scientific term wake maintenance zone, is a sleep phenomenon in which a person, after a prolonged period of staying awake, temporarily ceases to feel drowsy, often making it difficult to fall asleep when exhausted.

[4] The "second wind" phenomenon may have evolved as a survival mechanism as part of the fight-or-flight response, allowing sleep-deprived individuals briefly to function at a higher level than they would without sleep deprivation.

[5] One study presented a series of tasks of increasing difficulty to 16 young adults who had not slept in 35 hours and observed heightened activity in several brain regions using magnetic resonance imaging.

As late afternoon transitions into evening, changes in light levels can stimulate the suprachiasmatic nucleus in the brain to promote an arousal signal.

[11] At about 10:30 p.m. (depending on factors including the season and the condition of the individual), melatonin—the hormone responsible for preparing the body for sleep—peaks; a second wind may occur at this time if a person resists sleeping or fails to fall asleep before the peak.

Not only could this negate the soporific effectiveness of the medication, it may also cause users of the drug to experience disinhibition, hallucinations, or other dissociative phenomena, should they remain awake.