Effect of the GABA(A) agonist gaboxadol on nocturnal sleep and hormone secretion in healthy elderly subjects

Aging is associated with a dramatic decrease in sleep intensity and continu ity. The selective GABAA receptor agonist gaboxadol has been shown to incre ase non-REM sleep and the duration of the non-REM episodes in rats and slee p efficiency in young subjects and to enhance low-frequency activity in the electroencephalogram (EEG) within non-REM sleep in both rats and humans. I n this double-blind, placebo-controlled study, we investigated the influenc e of an oral dose of 15 mg of gaboxadol on nocturnal sleep and hormone secr etion (ACTH, cortisol, prolactin, growth hormone) in 10 healthy elderly sub jects (6 women). Compared with placebo, gaboxadol did not affect endocrine activity but significantly reduced perceived sleep latency, elevated self-e stimated total sleep time, and increased sleep efficiency by decreasing int ermittent wakefulness and powerfully augmented low-frequency activity in th e EEG within non-REM sleep. These findings indicate that gaboxadol is able to increase sleep consolidation and non-REM sleep intensity, without disrup ting REM sleep, in elderly individuals and that these effects are not media ted by a modulation of hormone secretion.