Objectives: The physiological and psychological responses to drug cue exposure have been assessed in substance abusers. However, there is no study to demonstrate whether the responses to drug cue exposure are diurnal dependence. The present study was to examine whether there was a variation in drug-related cue reactivity across the diurnal cycle among recently abstinent opiate addicts.
Methods: Four groups of 20 abstinent heroin dependent patients (n=80) were exposed to both neutral and drug-related videos at four separate times during the day: 8:00, 12:00, 16:00, and 20:00 h. Physiological and psychological responses, including heart rate, blood pressure, heroin craving, and subjective anxiety were assessed before and after each cue exposure.
Results: Drug cue significantly increased craving ratings compared to neutral cues across all the four separate times of day. Drug cue-induced craving was greater in the morning (8:00 am) than noon (12:00 pm), but was similar to evening assessments (8 pm). Drug cues also significantly increased anxiety, which positively correlated with cue-induced craving. Drug cues increased heart rate, systolic and diastolic blood pressures, which were not correlated with cue-induced craving or anxiety. However, no time effects were found on the three physiological measures.
Conclusions: Cue-induced craving could be profoundly affected by the time points of cue exposure, using cue-reactivity paradigm. The relative sensitivity of morning and evening assessments of drug craving suggests a need for replication and further research on mechanisms contributing to these diurnal variations.