### Controlled Trials Supporting Effectiveness 

Zaleplon (typically administered in doses of 5 mg, 10 mg, or 20 mg) has been studied in patients with chronic insomnia (n = 3,435) in 12 placebo- and active-drug-controlled trials. Three of the trials were in elderly patients (n = 1,019). It has also been studied in transient insomnia (n = 264). Because of its very short half-life, studies focused on decreasing sleep latency, with less attention to duration of sleep and number of awakenings, for which consistent differences from placebo were not demonstrated. Studies were also carried out to examine the time course of effects on memory and psychomotor function, and to examine withdrawal phenomena. 

### Transient Insomnia 

Normal adults experiencing transient insomnia during the first night in a sleep laboratory were evaluated in a double-blind, parallel-group trial comparing the effects of two doses of zaleplon (5 mg and 10 mg) with placebo. Zaleplon 10 mg, but not 5 mg, was superior to placebo in decreasing latency to persistent sleep (LPS), a polysomnographic measure of time to onset of sleep. 

### Chronic Insomnia 

#### Non-elderly patients

Adult outpatients with chronic insomnia were evaluated in three double-blind, parallel-group outpatient studies, one of 2 weeks duration and two of 4 weeks duration, that compared the effects of zaleplon at doses of 5 mg (in two studies), 10 mg, and 20 mg with placebo on a subjective measure of time to sleep onset (TSO). Zaleplon 10 mg and 20 mg were consistently superior to placebo for TSO, generally for the full duration of all three studies. Although both doses were effective, the effect was greater and more consistent for the 20 mg dose. The 5 mg dose was less consistently effective than were the 10 mg and 20 mg doses. Sleep latency with zaleplon 10 mg and 20 mg was on the order of 10 to 20 minutes (15% to 30%) less than with placebo in these studies. 

Adult outpatients with chronic insomnia were evaluated in six double-blind, parallel-group sleep laboratory studies that varied in duration from a single night up to 35 nights. Overall, these studies demonstrated a superiority of zaleplon 10 mg and 20 mg over placebo in reducing LPS on the first 2 nights of treatment. At later time points in 5, 14, and 28 night studies, a reduction in LPS from baseline was observed for all treatment groups, including the placebo group, and thus, a significant difference between zaleplon and placebo was not seen beyond 2 nights. In a 35 night study, zaleplon 10 mg was significantly more effective than placebo in reducing LPS at the primary efficacy endpoint on nights 29 and 30. 

#### Elderly patients

Elderly outpatients with chronic insomnia were evaluated in two 2 week, double-blind, parallel-group outpatient studies that compared the effects of zaleplon 5 mg and 10 mg with placebo on a subjective measure of time to sleep onset (TSO). Zaleplon at both doses was superior to placebo on TSO, generally for the full duration of both studies, with an effect size generally similar to that seen in younger persons. The 10 mg dose tended to have a greater effect in reducing TSO. 

Elderly outpatients with chronic insomnia were also evaluated in a 2 night sleep laboratory study involving doses of 5 mg and 10 mg. Both 5 mg and 10 mg doses of zaleplon were superior to placebo in reducing latency to persistent sleep (LPS). 

Generally in these studies, there was a slight increase in sleep duration, compared to baseline, for all treatment groups, including placebo, and thus, a significant difference from placebo on sleep duration was not demonstrated.