people take it for high level of anxiety or anxiety attacks as well as to go to sleep.... xanax is a marketing brand name for alprazolam-
from
wikipedia:
"Alprazolam has a calming effect, with the most common side effects being drowsiness, clumsiness, and to a lesser extent, fatigue, and headache. It can also have more adverse effects, such as blurred vision, slurred speech or dysarthria, and changes in personality. It may be habit forming and users often develop a tolerance to its initial effects, although its anxiolytic efficacy remains intact. Physical and/or psychological dependence may develop after several weeks of alprazolam treatment. There is now a general consensus among many psychiatrists that alprazolam (a so-called 'high-potency' benzodiazepine) poses a particularly high risk for abuse and dependence. Withdrawal after long-term use should be done slowly over a period of weeks to avoid serious withdrawal symptoms such as agitation, rebound anxiety, muscle cramps and possible seizures. Some patients may benefit from a more gradual dosage reduction and/or discontinuation and substitution with diazepam."