The prescription of hypnotics, mostly benzodiazepines, continues at a high level. One problem with their use is rebound insomnia: upon discontinuation sleep worsens compared with pretreatment levels. Factors influencing rebound include the type of subject, the duration of action of the hypnotic, the dosage and perhaps duration of treatment. The detection of rebound requires both sleep-laboratory and clinical studies with night-by-night analyses of individual patient data. This review concentrates on the newer compounds, (quazepam and zolpidem) which act selectively on subtypes of benzodiazepine receptors or bind atypically (zopiclone). It concludes that present evidence, while limited, is consistent with claims of less rebound potential than older benzodiazepine hypnotics of equivalent duration of action. Nevertheless, further rigorous studies are essential before these claims can be totally accepted.