Table 2.

Effect of zaleplon and zopiclone (ingested at 04.00 h) on various measures of sleep during exposure to a sound stimulus from the start of a second period (04.00 h–08.00 h) of nocturnal sleep (means ± s.d.).

		Zopiclone	Zaleplon
Measure	Placebo (n = 13)	7.5 mg (n = 13)	10 mg (n = 13)	20 mg (n = 12)
Latency to persistent sleep (min)	42.4 ± 21.1	33.5 ± 8.5	28.6 ± 13.2b	33.0 ± 12.8a
95% CI		−16.1, −1.3	−21.2, −6.4	−17.2, −2.1
Latency to REM+ (min)	39.6 ± 11.3	52.8 ± 16.9	44.5 ± 13.7	46.6 ± 18.0
95% CI		0.1, 26.9	−8.2, 18.5	−5.9, 21.6
Total sleep time	189.2 ± 31.7	204.9 ± 8.6b	199.2±14.9	200.2±14.7
95% CI		5.6, 24.7	0.3, 19.4	1.6, 21.2
Number of awakenings	7.0 ± 3.0	5.0 ± 3.0	7.0 ± 4.0	7.0 ± 3.0
95% CI		−3.7, 0.1	−1.6, 2.2	−1.6, 2.2
Awake (min)	8.7 ± 9.4	4.0 ± 4.1	6.3 ± 5.2	6.0 ± 5.6
95% CI		−8.1, −1.1	−5.8, 1.2	−6.4, 0.8
Stage 1 (min)	20.8 ± 8.5	13.4 ± 6.1b	16.5 ± 6.4	16.5 ± 6.6a
95% CI		−10.8, −3.8	−7.8, −0.8	−8.3, −1.1
Stage 2 (min)	98.8 ± 20.7	110.5 ± 19.3	100.4 ± 20.8	97.5 ± 14.6
95% CI		−1.6, 24.3	−11.2, 14.6	−13.9, 12.6
Stage 3 (min)	7.8 ± 7.1	22.1 ± 13.6b	13.6 ± 8.7	17.5 ± 8.4
95% CI		6.6, 21.9	−1.9, 13.3	1.6, 17.2
Stage 4 (min)	0.4 ± 1.4	4.5 ± 8.1	5.5 ± 10.1	7.3 ± 7.6
95% CI		−1.9, 9.8	−1.1, 10.6	1.5, 13.5
REM+ (min)	62.4 ± 18.6	54.4 ± 16.0	64.3 ± 14.7	61.5 ± 12.3
95% CI		−18.6, 2.3	−8.5, 12.3	−11.9, 9.5
Stage 1 (%)	11.0 ± 5.0	6.0 ± 3.0	8.0 ± 3.0	8.0 ± 3.0
95% CI		−6.2, −2.2	−4.6, −0.6	−4.8, −0.7
Stage 2 (%)	49.0 ± 7.0	53.0 ± 8.0	49.0 ± 9.0	47.0 ± 6.0
95% CI		−2.3, 9	−6.4, 4.9	−7.9, 3.8
Stage 3 (%)	4.0 ± 4.0	11.0 ± 7.0	7.0 ± 4.0	9.0 ± 4.0
95% CI		2.6, 10.3	−1.4, 6.3	0.3, 8.1
Stage 4 (%)	0.0 ± 1.0	2.0 ± 4.0	3.0 ± 5.0	4.0 ± 4.0
95% CI		−0.8, 4.9	−0.4, 5.3	0.8, 6.7
REM+ (%)	31.0 ± 8.0	26.0 ± 8.0	31.0 ± 7.0	30.0 ± 5.0
95% CI		−9.7, 0.3	−4.6, 5.4	−6.4, 3.9

^aP < 0.0167,

^bP < 0.0033 (the 5% and 1% significance levels, respectively, adjusted for multiple comparisons) compared with placebo.

⁺REM: Rapid eye movement sleep.