The medication modafinil has been shown to reduce cocaine use in some cocaine users. The investigators have shown that modafinil taken in the morning improves sleep in chronic cocaine users. The investigators hypothesize that the beneficial effects of modafinil in reducing cocaine use may be related to specific effects modafinil has on sleep. This study will measure sleep and cocaine use in cocaine dependent persons who are trying to stop using cocaine, and will test the connection between modafinil's effects on sleep and cocaine use.

Inclusion Criteria:

• 25-50 years of age;
• voluntary, written, informed consent;
• seeking but not currently enrolled in treatment for cocaine use;
• self-reported, current use of cocaine by smoked or intravenous route at least one time each week in the past month, with ≥1g used within a single 24-hour period and ≥3g used in the month;
• positive urine test for cocaine (benzoylecognine) at the time of screening and study start
• dependence on cocaine in the past year as measured by a score ≥ 3 on the Severity of Dependence Scale(Kaye and Darke, 2002);
• chronic use in the past year as determined by self-reported use in at least 9 of the past 12 months;
• lifetime diagnosis of cocaine dependence with a duration of at least 2 years as determined by the Structured Clinical Interview for DSM-IV (SCID).

Exclusion Criteria:

• evidence of any neurological condition or a chronic medical condition including diabetes, cardiovascular disease or history of cardiac problems, HIV-seropositivity, liver disease, hypertension, asthma requiring daily medication, dementia, movement disorder, history of head trauma with loss of consciousness, sleep apnea, narcolepsy, restless leg syndrome, periodic limb movement disorder, REM sleep disorder, pharmacological treatment for insomnia of any type within the past 6 months, glaucoma, severe respiratory insufficiency, seizure disorder, or if in the past three months they have taken any medications that affect sleep, or are currently taking any regularly dosed prescription medication or any prn medication that is used on average more than 1x/week
• evidence of chronic sleep disorder including sleep apnea, narcolepsy, periodic limb movement disorder, restless leg syndrome as determined by medical history, Sleep Disorders Questionnaire(Douglass, 1994), or by polysomnography (following enrollment)
• current dependence on any drugs other than cocaine or nicotine or lifetime dependence on alcohol, benzodiazepines, or opiates, or any non-substance related Axis I disorder as determined by SCID
• current use of alcohol in excess of 3x/week AND 21 standard drinks/week in the past month or non-zero breathalyzer at screening or study start
• current use of cannabis in the past month
• positive urine toxicology test for opiates, methadone, amphetamines, barbiturates, benzodiazepines, PCP, methaquolone, and propoxyphene at the time of screening or positive test for any of those listed plus cannabis at the time of study start
• pregnancy as determined by serum β-HCG at screening or lactating per report
• females: unwillingness to use barrier contraceptives during sexual intercourse for the duration of the study
• known hypersensitivity to modafinil.