A 12-week, randomized, double-blind, placebo-controlled study evaluating the effect of eszopiclone 2 mg on sleep/wake function in older adults with primary and comorbid insomnia - Ancoli-Israel, S; Krystal, AD; McCall, WV; Schaefer, K; Wilson, A; Claus, R; Rubens, R; Roth, T (Sleep, 2010)