CHANGES OF CYCLIC ALTERNATING PATTERN (CAP) PARAMETERS IN SITUATIONALINSOMNIA UNDER BROTIZOLAM AND TRIAZOLAM

The standardized scoring criteria of sleep can serve as a rough tool f or monitoring the effects of psychoactive compounds, both in normal sl eepers and in insomniac patients. More sensitive information on the im pact of perturbing factors and drugs during sleep is supplied by the c yclic alternating pattern (CAP)parameters. In particular, CAP rate, wh ich measures the amount of arousal instability during NREM sleep, has been proved of high reliability in a variety of clinical and pharmacol ogical settings. The present study aimed at evaluating the activity of brotizolam (Br) 0.25 mg and triazolam (Tr) 0.25 mg on both convention al and CAP parameters in a model of situational insomnia of intermedia te severity. Six middle-aged healthy subjects (three males and three f emales, aged 40-55 years) with no complaints about sleep, underwent a polysomno-graphic investigation according to a doubler-blind crossover design: placebo without noise (night 1), placebo with noise (night 2) , brotizolam or triazolam without noise (nights 3 and 5), brotizolam o r triazolam with noise (nights 4 and 6). The unperturbed nights consis ted of standard recording conditions in a sound-protected sleep labora tory, whereas situational insomnia was accomplished by means of contin uous white noise at 55 dBA delivered throughout the night. Subjects re ceived medication orally at bedtime. An interval of at least 48 h was secured between consecutive recordings in the same individual. Compare d to baseline conditions, situational insomnia was characterized by a shorter amount of total sleep (-40 min) and by an extension of intrasl eep awakenings (+ 62 min). Compared to triazolam, during the perturbed nights brotizolam guaranteed a longer duration of sleep time (Br: 462 min versus Tr: 443 min), a reduced length of intrasleep awakenings (B r: 14 min versus Tr: 34 min) and a lower percentage of stage 1 (Br: 3. 6% versus Tr: 5.8%). However, on the basis of the statistical informat ion supplied by the conventional sleep parameters, the drug nights cou ld not be clearly discriminated from the placebo nights. By contrast, both brotizolam and triazolam significantly reduced (P < 0.0001) the p athological amounts of CAP Rate (Br: -17%; Tr: -15%) during acoustic p erturbation, while they preserved the physiological values of CAP para meters under basal conditions. In essence, CAP parameters reveal the p rotective activity of hypnotic compounds in situational insomnia even in the absence of macrostructural alterations.