Residual Effects on Memory and Psychomotor Performance of Zaleplon and Other Hypnotic Drugs

Long-acting benzodiazepine hypnotics are known to cause cognitive and psychomotor impairment throughout the day after a nocturnal dose. Patients using these drugs are overrepresented in injurious falls and traffic accidents. Recognition of this problem has led to the development of compounds that are eliminated rapidly and bind selectively to only 1 of the 3 known benzodiazepine receptors. Zaleplon, the newest in this class, is the most rapidly eliminated of the hypnotics. Some clinicians speculate that zaleplon may be taken in the approved 10-mg dosage for inducing sleep either at normal bedtime or after a nocturnal awakening without risk of residual sedation affecting safety. Extensive research has been devoted to measuring the effects of zaleplon, 10 and 20 mg, on memory, psychomotor performance, and driving at various times after ingestion. The effects of zaleplon have been compared with those of other short-acting hypnotics, notably the nonbenzodiazepines zolpidem and zopiclone. These comparisons have shown that only zaleplon, 10 mg, can be taken to initiate or resume sleep 4 or more hours before final awakening with little risk of the psychomotor impairment that could compromise patient safety. The effect of zaleplon on mnemonic functions, at the same time, is uncertain. If zaleplon affects memory, the extent is not only limited but is also less than that of comparator hypnotics.