Figure 4. Return to sleep latency.

n = 51 for all groups owing to technical difficulties with polysomnography in 4 participants and 1 participant never awakened during the night in 1 treatment condition. *P ≤ .0001 vs. placebo; ^†P < .05 vs zolpidem based on an unstructured covariance matrix; model adjusted for treatment, sequence, and period as fixed effects, and a repeated effect of participant within sequence. ER = extended release, LS = least squares, SE = standard error.