Sleep spindle and delta changes during chronic use of a short-acting and a long-acting benzodiazepine hypnotic.

Twenty-one medically screened insomniacs were studied over 59 nights in a double-blind, parallel groups design study. The 7 patients receiving a short-acting (triazolam) and the 7 receiving a long-acting (flurazepam) benzodiazepine hypnotic showed a similar pattern and magnitude of sleep EEG changes, especially during the latter part of the 37-night treatment period. Both groups significantly increased sleep spindle rate and decreased delta count per minute. The patterns of withdrawal were also similar. Plasma levels of N-desalkylflurazepam were not significantly related to the magnitude of EEG changes.