The effects of nicotine withdrawal that come from stopping a tobacco habit can include both nervousness and somnolence as well as the more well-known symptoms of increased appetite and weight gain. Nicotine can act as a mild stimulant which explains the sleep problems associated with withdrawal. This compound alters brain chemicals involved in sleep and produces changes in brain wave patterns. Sleep changes with long term use include increased time in getting to sleep and reduced REM sleep. It is not considered to be a good sleep aid.
Cocaine potentiates certain brain chemicals.
Cocaine's arousing and addictive influences stem from its effects on the brain chemical, dopamine, which is involved in wakefulness and body movement. Sleep changes include reduced stage 3 and stage 4 NREM sleep and reduced REM sleep. When cocaine is discontinued, the individual becomes very sleepy and may feel that more cocaine is necessary just to function. Cocaine is addictive particularly when used in the very short-acting form known as 'crack'. They are powerful stimulants that are not unlike cocaine in many respects.