The aim of the present study was to compare the hangover effects of night-time administration of triazolam (0.25 mg), flunitrazepam (1 mg) and quazepam (15 mg) in healthy subjects. Daytime sleepiness and performance level following the night-time administration of the drugs were assessed using Standford Sleepiness Scale (SSS), Sleep Evaluation Questionnaire (SEQ), Multiple Sleep Latency Test (MSLT), actigraphy recordings and Continuous Performance Test (CPT). Fifteen healthy volunteers were given one of the three hypnotics at each drug session, which lasted for 1 week, in a single-blind cross-over fashion. No significant between-drug difference was observed for the psychomotor performance assessed by CPT. Subjective hangover effects assessed by SSS and SEQ in the morning were prominent for flunitrazepam and quazepam relative to triazolam, whereas objective indices such as MSLT or activity counts obtained in actigraphy indicated a marked hangover effect of quazepam compared with the other two compounds restrictively in the afternoon, which were nearly in accordance with their pharmacokinetic profiles.