Polysomnographic findings in a cohort of chronic insomnia patients with benzodiazepine abuse

Abstract

Study objectives: To evaluate sleep modifications induced by chronic benzodiazepine (BDZ) abuse.

Methods: Cohort study, comparison of sleep measures between BDZs abusers and controls. Drug Addiction Unit (Institute of Psychiatry) and Unit of Sleep Disorders (Institute of Neurology) of the Catholic University in Rome. Six outpatients affected by chronic BDZ abuse were enrolled, (4 men, 2 women, mean age 53.3 ± 14.8, range: 34-70 years); 55 healthy controls were also enrolled (23 men, 32 women, mean age 54.2 ± 13.0, range: 27-76 years). All patients underwent clinical evaluation, psychometric measures, ambulatory polysomnography, scoring of sleep macrostructure and microstructure (power spectral fast-frequency EEG arousal, cyclic alternating pattern [CAP]), and heart rate variability.

Results: BDZ abusers had relevant modification of sleep macrostructure and a marked reduction of fast-frequency EEG arousal in NREM (patients: 6.6 ± 3.7 events/h, controls 13.7 ± 4.9 events/h, U-test: 294, p = 0.002) and REM (patients: 8.4 ± 2.4 events/h, controls 13.3 ± 5.1 events/h, U-test: 264, p = 0.016), and of CAP rate (patients: 15.0 ± 8.6%, controls: 51.2% ± 12.1%, U-test: 325, p < 0.001).

Discussion: BDZ abusers have reduction of arousals associated with increased number of nocturnal awakenings and severe impairment of sleep architecture. The effect of chronic BDZ abuse on sleep may be described as a severe impairment of arousal dynamics; the result is the inability to modulate levels of vigilance.

Keywords: Abuse; arousal; benzodiazepines; cyclic alternating pattern; polysomnography; sleep.

Figure 1. Twenty-four-hour sleep hypnograms in BDZ abusers

Figure 2. Histograms of relative power spectra in BDZ abusers and controls