A need to take larger and larger doses of sleeping pills to avoid insomnia is an indication of

A) narcolepsy.
B) tolerance.
C) sleep apnea.
D) REM rebound.

Tolerance is the need to take larger and larger doses of a drug to achieve the same effect, which is a common phenomenon with sleeping pills. Narcolepsy is a sleep disorder characterized by sudden and uncontrollable episodes of sleep during the day. Sleep apnea is a sleep disorder in which breathing repeatedly stops and starts during sleep. REM rebound is the phenomenon of experiencing an increase in REM sleep after a period of REM sleep deprivation.