Although alcohol can work as a sleep aid in the short term, it tends to have a lot of negative side effects in the long term. Small amounts of alcohol used as a nightcap may lead to waking in the middle of the night. Large amounts of alcohol can lead to hangovers, oversleeping, or even alcohol withdrawal syndrome if continued over long periods of time. Alternatives to alcohol as a sleep aid include the following:

OTC (Over The Counter) Sleep Aids
Diphenhydramine e.g. Benadryl
Doxylamine succinate e. g. Unisom Sleep Tabs

WARNING: because of the danger of liver damage, people who drink alcohol should avoid sleep aids which contain Tylenol (acetaminophen) such as Tylenol PM.

Herbal Sleep Aids
Valerian
Melatonin
Tryptophan

Prescription Sleep Aids
Ambien
Lunesta
Remeron
Trazodone

Other ways to improve sleep quality
The Mayo Clinic Sleep page

For more detailed information about alcohol, sleep, and harm reduction please buy a copy of The HAMS Book.