Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Sleep latency
RCT 4-armed trial	48 people with insomnia aged 60 to 80 years	Median subjective sleep latency 2 days 43.8 minutes with zaleplon 2 mg 30.0 minutes with zaleplon 5 mg 25.0 minutes with zaleplon 10 mg 45.0 minutes with placebo	Reported as significant for zaleplon 5 mg and 10 mg only P = 0.654 for zaleplon 2 mg v placebo P = 0.017 for zaleplon 5 mg v placebo P <0.001 for zaleplon 10 mg v placebo	Effect size not calculated	zaleplon (5 mg and 10 mg only)
RCT 4-armed trial	48 people with insomnia aged 60 to 80 years	Median objective sleep latency 2 days 27.0 minutes with zaleplon 2 mg 23.4 minutes with zaleplon 5 mg 14.6 minutes with zaleplon 10 mg 30.1 minutes with placebo	P = 0.015 for zaleplon 2 mg v placebo P <0.001 for zaleplon 5 mg v placebo P <0.001 for zaleplon 10 mg v placebo	Effect size not calculated	zaleplon (2 mg, 5 mg, and 10 mg)
RCT 4-armed trial	549 people with primary insomnia aged 65 years and over	Median subjective sleep latency in minutes 7 days with zaleplon 5 mg with zaleplon 10 mg with placebo Absolute results reported graphically	Reported that zaleplon 10 mg significantly reduced sleep latency compared with placebo; P <0.001 Reported no significant difference for zaleplon 5 mg v placebo	Effect size not calculated	zaleplon (10 mg only)
RCT 4-armed trial	549 people with primary insomnia aged 65 years and over	Median subjective sleep latency 14 days –36.75 minutes with zaleplon 5 mg Reported graphically with zaleplon 10 mg –11.79 minutes with placebo Absolute results reported graphically	P <0.001 for zaleplon 5 mg or 10 mg v placebo	Effect size not calculated	zaleplon (5 mg and 10 mg)
RCT 3-armed trial	422 people aged 65 years or over with primary insomnia for 3 months or more	Median subjective sleep latency in minutes 7 and 14 days with zaleplon 5 mg with zaleplon 10 mg with placebo Absolute numbers not reported	P <0.001 for zaleplon 5 mg and 10 mg v placebo at either time frame	Effect size not calculated	zaleplon (5 mg and 10 mg)
Total sleep time
RCT 4-armed trial	48 people with insomnia aged 60 to 80 years	Median subjective total sleep time 2 days 330.0 minutes with zaleplon 2 mg 330.0 minutes with zaleplon 5 mg 367.5 minutes with zaleplon 10 mg 345.0 minutes with placebo	P = 0.776 for zaleplon 2 mg v placebo P = 0.140 for zaleplon 5 mg v placebo P = 0.140 for zaleplon 10 mg v placebo		Not significant
RCT 4-armed trial	48 people with insomnia aged 60 to 80 years	Median objective sleep duration 2 days 364.6 minutes with zaleplon 2 mg 375.3 minutes with zaleplon 5 mg 365.0 minutes with zaleplon 10 mg 344.6 minutes with placebo	P = 0.239 for zaleplon 2 mg v placebo P = 0.003 for zaleplon 5 mg v placebo P = 0.030 for zaleplon 10 mg v placebo	Effect size not calculated	zaleplon (5 mg and 10 mg only)
RCT 4-armed trial	549 people with primary insomnia aged 65 years and over	Median subjective total sleep time (improvement from baseline) 7 days Result reported graphically with zaleplon 5 mg 345 (+28.86) minutes with zaleplon 10 mg 318 (+23.48) minutes with placebo	P <0.05 for zaleplon 10 mg v placebo No significant difference for zaleplon 5 mg v placebo	Effect size not calculated	zaleplon (10 mg only)
RCT 4-armed trial	549 people with primary insomnia aged 65 years and over	Median subjective total sleep time (improvement from baseline) 14 days with zaleplon 5 mg with zaleplon 10 mg with placebo Absolute results reported graphically	No significant difference for either zaleplon 5 mg or 10 mg v placebo		Not significant
RCT 3-armed trial	422 people aged 65 years or over with primary insomnia for 3 months or more	Median subjective total sleep time (improvement from baseline) 7 days 342.0 (+16.3) minutes with zaleplon 5 mg 342.9 (+38.6) minutes with zaleplon 10 mg 346.1 (+24.1) minutes with placebo	P <0.05 for both zaleplon 5 mg and 10 mg v placebo	Effect size not calculated	zaleplon (5 mg or 10 mg)
RCT 3-armed trial	422 people aged 65 years or over with primary insomnia for 3 months or more	Median subjective total sleep time (improvement from baseline) 7 days 351.7 (+26.0) minutes with zaleplon 5 mg 351.4 (+47.1) minutes with zaleplon 10 mg 346.1 (+24.1) minutes with placebo	No significant difference for either zaleplon 5 mg or 10 mg v placebo		Not significant
Subjective sleep quality
RCT 4-armed trial	549 people with primary insomnia aged 65 years and over	Median subjective sleep-quality score, from 1 = excellent to 7 = poor (improvement from baseline) 7 days 3.83 (+0.46) with zaleplon 5 mg 3.67 (+0.46) with zaleplon 10 mg 4.00 (+0.29) with placebo	P <0.05 for zaleplon 10 mg v placebo No significant difference for zaleplon 5 mg v placebo	Effect size not calculated	zaleplon (10 mg only)
RCT 4-armed trial	549 people with primary insomnia aged 65 years and over	Median subjective sleep-quality score, from 1 = excellent to 7 = poor (improvement from baseline) 14 days 3.75 (+0.54) with zaleplon 5 mg 3.63 (+0.51) with zaleplon 10 mg 4.00 (+0.29) with placebo	Reported no significant difference for zaleplon 5 mg v placebo		Not significant
RCT 3-armed trial	422 people aged 65 years or over with primary insomnia for 3 months or more	Median subjective sleep-quality score, from 1 = excellent to 7 = poor (improvement from baseline) 7 days 3.80 (+0.40) with zaleplon 5 mg 3.80 (+0.50) with zaleplon 10 mg 3.90 (+0.30) with placebo	P <0.01 for zaleplon 10 mg and 5 mg v placebo	Effect size not calculated	zaleplon (5 mg and 10 mg)
RCT 3-armed trial	422 people aged 65 years or over with primary insomnia for 3 months or more	Median subjective sleep-quality score, from 1 = excellent to 7 = poor (improvement from baseline) 14 days 3.70 (+0.50) with zaleplon 5 mg 3.80 (+0.50) with zaleplon 10 mg 3.80 (+0.40) with placebo	P <0.05 for zaleplon 10 mg and 5 mg v placebo	Effect size not calculated	zaleplon (5 mg and 10 mg)
Number of awakenings
RCT 4-armed trial	48 people with insomnia aged 60 to 80 years	Median subjective number of awakenings 2 days 3.0 with zaleplon 2 mg 3.0 with zaleplon 5 mg 2.5 with zaleplon 10 mg 2.8 with placebo	P = 0.671 for zaleplon 2 mg v placebo P = 0.906 for zaleplon 5 mg v placebo P = 0.045 for zaleplon 10 mg v placebo	Effect size not calculated	zaleplon (10 mg only)
RCT 4-armed trial	48 people with insomnia aged 60 to 80 years	Median objective number of awakenings 2 days 21.0 with zaleplon 2 mg 19.5 with zaleplon 5 mg 18.8 with zaleplon 10 mg 19.5 with placebo	Not significant for each dose of zaleplon v placebo P = 0.872 for zaleplon 2 mg v placebo P = 0.623 for zaleplon 5 mg v placebo P = 0.969 for zaleplon 10 mg v placebo		Not significant
RCT 4-armed trial	549 people with primary insomnia aged 65 years and over	Median subjective number of awakenings 7 days 1.8 with zaleplon 5 mg 1.8 with zaleplon 10 mg 1.8 with placebo	No significant difference for either zaleplon 5 mg or 10 mg v placebo		Not significant
RCT 4-armed trial	549 people with primary insomnia aged 65 years and over	Median subjective number of awakenings 7 days 1.9 with zaleplon 5 mg 1.7 with zaleplon 10 mg 1.9 with placebo	No significant difference for either zaleplon 5 mg or 10 mg v placebo		Not significant
RCT 3-armed trial	422 people aged 65 years or over with primary insomnia for 3 months or more	Median subjective number of awakenings 7 days 2.0 with zaleplon 5 mg 2.0 with zaleplon 10 mg 2.0 with placebo	No significant difference for either zaleplon 5 mg or 10 mg v placebo		Not significant
RCT 3-armed trial	422 people aged 65 years or over with primary insomnia for 3 months or more	Median subjective number of awakenings 14 days 2.0 with zaleplon 5 mg 1.0 with zaleplon 10 mg 2.0 with placebo	No significant difference for either zaleplon 5 mg or 10 mg v placebo		Not significant