Abstract
STUDY OBJECTIVES: During abstinence, chronic cocaine users experience an objective worsening of sleep that is perceived as qualitatively improving. This phenomenon has been termed "occult insomnia." The objective of this study was to determine whether chronic cocaine users experience positive sleep state misperception during abstinence. METHODS: Forty-three cocaine-dependent persons were admitted to an inpatient research facility for 12 days and 11 nights to participate in a treatment study of modafinil. Polysomnographic sleep recordings were performed on study nights 3, 4, 10, and 11, when participants were on average 1 and 2 weeks abstinent from cocaine. Participants also completed sleep diary questionnaires every evening before bed and every morning upon awakening. Polysomnographic and sleep diary measurements of total sleep time, sleep latency, time awake after sleep onset, and time in bed after final awakening were compared. RESULTS: Chronic cocaine users accurately reported total sleep time after 1 week of abstinence but overreported total sleep time by an average of 40 min after 2 weeks of abstinence. Underestimating sleep latency and time spent awake after sleep onset were responsible for this difference. CONCLUSIONS: Positive sleep state misperception is revealed in chronic cocaine users after 2 weeks of abstinence and is consistent with the previously identified "occult insomnia" in this population.