The GABA(A) agonist gaboxadol improves the quality of post-nap sleep

Rationale: Previous studies demonstrated that gaboxadol, a selective GABA(A ) agonist, increases both non-REM sleep and EEG delta activity within non-R EM sleep in rats and slow wave sleep (SWS) as well as low-frequency activit y in the EEG within non-REM sleep in healthy humans under normal conditions . Objective: Because the hypnotic actions of drugs may be more readily demo nstrated under conditions of poor sleep quality, we investigated the influe nce of gaboxadol on postnap sleep. Methods: In a randomized, placebo-contro lled cross-over study using a late afternoon nap model, we assessed the eff ects of a single oral dose of 20 mg gaboxadol on disturbed nighttime sleep in young, healthy subjects. Results: Comparisons of visually scored sleep p arameters between baseline and placebo postnap nights showed that the nap p rolonged sleep latency, decreased total sleep time and SWS and attenuated d elta, theta and alpha activity in the EEG within non-REM sleep. Compared wi th the placebo postnap night, gaboxadol tended to shorten sleep latency, si gnificantly decreased intermittent wakefulness, increased total sleep time and SWS and enhanced delta and theta activity in the non-REM EEG. Furthermo re, gaboxadol increased subjective sleep quality. Conclusions: These data s how that gaboxadol counteracts the disrupting, effects of a nap on subseque nt sleep and suggest that, in addition to promoting deep sleep and sleep ma intenance, gaboxadol is able to facilitate sleep initiation and thus, exhib its significant hypnotic actions under conditions in which sleep quality is experimentally reduced.