Hypnotic Medications and Memory: Effect of Drug Exposure During the Night

A growing body of evidence has demonstrated that sleep promotes memory consolidation in
healthy individuals. However, little research has been conducted regarding the effect of
hypnotics on sleep-dependent memory. One study found that zopiclone (7.5 mg), but not
brotizolam (0.25 mg), impaired sleep-dependent memory consolidation in normal sleepers.
Another study reported significant impairment of sleep-dependent memory on a motor task with
triazolam (0.375 mg), but not with zolpidem immediate release (10 mg). These studies
provide some evidence that sedative-hypnotic drugs may impair sleep-dependent memory
consolidation, but further investigation is clearly needed in this area. Because hypnotics
are commonly prescribed for insomnia, it is important to determine if there is a significant
risk of impairment in sleep-dependent memory consolidation associated with these
medications. Further, investigation of alternative doses and drug regimens upon memory
consolidation appears warranted.

The purpose of the current study is to determine the effect of two hypnotic medications on
sleep-dependent memory consolidation in normal sleepers. Zolpidem extended release, which
will be active for most of the sleep period when administered at bedtime, will be compared
to zaleplon, which will be active for half of the sleep period when administered in the
middle of the night. This comparison allows us to address the question of whether a few
hours of drug-free sleep results in better memory consolidation than sleep with drug
throughout the night.