The relationship between cocaine self-administration and actigraphy-based measures of sleep in adult rhesus monkeys.

Rationale: Clinical trials show that chronic cocaine users suffer from sleep disturbances and preclinical research has shown that acute sleep deprivation increases the rate of cocaine self-administration in rats.

Objective: This study examined the effect of cocaine self-administration on behavioral indices of sleep and alternatively the effect of sleep disruption on cocaine-maintained responding by rhesus monkeys.

Methods: Seven adult rhesus monkeys, fitted with Actical® activity monitors, were trained to respond under a concurrent choice paradigm with food (three 1.0-g pellets) and cocaine (0.003-0.3 mg/kg) or saline presentation. For each monkey, the lowest preferred dose of cocaine (>80% cocaine choice) was determined. Activity data were analyzed during lights out (2000-0600) to determine sleep efficiency, sleep latency, and total activity counts. Subsequently, the monkeys' sleep was disrupted (every hour during lights-out period) the night prior to food-cocaine choice sessions.

Results: Self-administration of the preferred dose of cocaine resulted in a significant decrease in sleep efficiency, with a significant increase in total lights-out activity. Sleep disruption significantly altered behavioral indices of sleep, similar to those seen following cocaine self-administration. However, sleep disruption did not affect cocaine self-administration under concurrent choice conditions.

Conclusions: Based on these findings, cocaine self-administration does appear to disrupt behavioral indices of sleep, although it remains to be determined if treatments that improve sleep measures can affect future cocaine taking.