Subchronic Effects of Eszopiclone (Lunesta) on Pain Behavior and Circuitry in Primary Insomnia

It is well known that chronic pain syndromes are associated with alterations in sleep continuity and sleep architecture. Similarly, recent evidence indicates that sleep deprivation interferes with normal pain perception producing hyperalgesic changes, and with the regular analgesic effects of certain pain drugs (reviewed in Kundermann B et al., 2004). However, the role of the nonbenzodiazepine hypnotic agents in pain perception is not well understood. Lunesta (eszopiclone), unlike other nonbenzodiazepine sleep medications, is approved for long-term use (no significant addictive effects of the drug are observed following the treatment of up to 6mo). Its antinociceptive properties have not been examined and, if found, could potentiate the use of this drug for pain control, especially in patients with comorbid chronic pain and insomnia.

The objective of this proposal is to use Functional Magnetic Resonance Imaging (fMRI) with an experimental pain paradigm in a group of chronic insomnia patients. The study will consist of three sessions, the first of which will include questionnaires, and a mental and physical health evaluation including an EKG and blood draw. Following the initial screening session subjects will be randomly assigned to either the study drug or placebo groups, and complete 2 additional identical study sessions using fMRI. The first fMRI session will be before taking the drug/placebo, and the second session will be after taking the study drug/placebo nightly for 1 week. During these fMRI sessions, subjects will undergo psychophysical testing of their sensitivity to warmth and heat and will rate various temperatures for pain intensity and pain unpleasantness. Subjects will also complete additional tasks including motor inhibition and face matching during scanning.