Article Figures & Data
Figures
- Figure 1.
Study time line. The experimental time line for each session for Study 1 (a) and Study 2 (b). On the eve of the experimental day, subjects slept in the laboratory with a bedtime of 11:00 P.M. and a wake time of 5:00 A.M. In study 2, participants took cognitive tests between 6:00 and 8:00 A.M. At 8:30 A.M., subjects were reattached to the PSG monitor, given their medication, and allowed to nap until 90 min of total sleep time was obtained. At 3:00 P.M., subjects were retested on the cognitive tasks.
- Figure 2.
Drug effects on minutes in each sleep stage and spindle density. a, Study 1 compares 5 and 10 mg of ZOL (black bars), 2.5 and 3 g of SO (gray bars), and placebo (white bars). b, Study 2 compares 10 mg of ZOL (black bars), 2.5 g of SO (gray bars), and placebo (white bars). Statistical comparisons are between drug conditions and placebo. ***p < 0.001; **p < 0.01; *p < 0.05.
- Figure 3.
Cognitive performance by drug condition. Difference scores for the verbal paired associate task, the visual texture discrimination task, and the motor sequence task for the three drug conditions: 10 mg of ZOL, 2.5 g of SO, and placebo. Statistical comparisons are between drug conditions and placebo. **p < 0.005; *p < 0.05.
- Figure 4.
Sleep features and memory performance. a, Spindle density in each drug condition (ZOL, black circle; SO, gray circle; placebo, white circle) is shown relative to change scores in verbal memory. b, REM minutes in each drug are shown relative to change scores in perceptual learning. c, Spindle density in each drug condition is shown relative to change scores in motor learning.
Tables
Placebo Sodium oxybate (2.5 g) Sodium oxybate (3 g) Zolpidem (5 mg) Zolpidem (10 mg) Statistic Study 1 TSTact (min) 397 ± 59 396 ± 52 388 ± 63 413 ± 56 408 ± 59 F(4,44) = 0.70, p = 0.60 SEact 77 ± 8 78 ± 8 76 ± 9 80 ± 7 78 ± 7 F(4,44) = 0.68, p = 0.62 WASOact (min) 98 ± 43 89 ± 35 96 ± 36 83 ± 34 91 ± 36 F(4,44) = 0.38, p = 0.81 Study 2 TSTact (min) 376 ± 7.2 381 ± 6.5 372 ± 6.9 F(2,54) = 0.80, p = 0.45 SEact 81 ± 1.2 81 ± 1.0 80 ± 1.3 F(2,54) = 1.14, p = 0.32 WASOact (min) 71 ± 4.6 71 ± 4.7 75 ± 4.9 F(2,54) = 0.63, p = 0.53 Placebo Sodium oxybate (2.5 g) Sodium oxybate (3 g) Zolpidem (5 mg) Zolpidem (10 mg) Statistic Study 1 TSTnight (min) 322 ± 30 313 ± 44 333 ± 17 321 ± 29 323 ± 42 F(4,72) = 1.38, p = 0.28 SEnight 89 ± 7 86 ± 12 92 ± 4 89 ± 8 89 ± 11 F(4,72) = 1.06, p = 0.41 SLnight (min) 16 ± 16 18 ± 26 9 ± 5 12 ± 15 15 ± 24 F(4,72) = 1.00, p = 0.43 WASOnight (min) 20 ± 17 29 ± 32 18 ± 11 25 ± 27 21 ± 27 F(4,72) = 0.49, p = 0.73 Stage 1 (min) 12 ± 6 13 ± 7 12 ± 8 12 ± 5 12 ± 6 F(4,72) = 0.23, p = 0.92 Stage 2 (min) 175 ± 21 171 ± 23 183 ± 24 166 ± 24 172 ± 34 F(4,72) = 2.32, p = 0.10 SWS (min) 77 ± 26 77 ± 25 80 ± 24 79 ± 22 81 ± 28 F(4,72) = 0.25, p = 0.90 REM (min) 57 ± 17 50 ± 19 57 ± 17 62 ± 18 56 ± 20 F(4,72) = 2.07, p = 0.13 Study 2 TSTnight (min) 319 ± 26 317 ± 30 321 ± 24 F(2,58) = 0.46, p = 0.62 SEnight 86 ± 18 88 ± 8 87 ± 18 F(2,58) = 0.19, p = 0.82 SLnight (min) 13 ± 9 18 ± 14 14 ± 12 F(2,58) = 0.46, p = 0.62 WASOnight (min) 23 ± 21 25 ± 26 23 ± 18 F(2,58) = 0.06, p = 0.93 Stage 1 (min) 14 ± 9 15 ± 10 13 ± 9 F(2,58) = 0.71, p = 0.49 Stage 2 (min) 190 ± 34 190 ± 36 192 ± 31 F(2,58) = 0.11, p = 0.89 SWS (min) 71 ± 22 70 ± 30 71 ± 25 F(2,58) = 0.07, p = 0.92 REM (min) 45 ± 20 42 ± 14 46 ± 13 F(2,58) = 0.53, p = 0.59 Placebo Sodium oxybate (2.5 g) Sodium oxybate (3 g) Zolpidem (5 mg) Zolpidem (10 mg) Statistic TSTnap (min) 86 ± 4.5 91 ± 1.7 91 ± 4.6 85 ± 2.5 95 ± 1.4 F(4,72) = 2.00, p = 0.10, partial eta2 = 0.1 Sleep latencynap (min) 11.7 ± 2.0 8.2 ± 1.0 9.0 ± 2.1 13.4 ± 1.7 10.6 ± 1.5 F(4,72) = 3.00, p = 0.06, partial eta2 = 0.11 WASOnap (min) 16.7 ± 4.9 10 ± 5.0 5.5 ± 3.0 14.6 ± 4.8 6.5 ± 1.3 F(4,71) = 3.26, p = 0.01, partial eta2 = 0.15 Sleep efficiencynap 76 ± 4.2 85.4 ± 2.9 87.1 ± 4.5 77.4 ± 3.7 85.5 ± 1.8 F(4,72) = 3.97, p = 0.006, partial eta2 = 0.18 C4 spindle density 2.70 ± 0.20 1.32 ± 0.20 1.14 ± 0.23 3.12 ± 0.39 3.49 ± 0.46 F(4,72) = 24.84, p < 0.001, partial eta2 = 0.58 C3 spindle density 3.11 ± 0.36 1.71 ± 0.25 1.44 ± 0.25 3.55 ± 0.40 4.08 ± 0.48 F(4,72) = 19.99, p < 0.001, partial eta2 = 0.52 Stage 1 (min) 9.73 ± 0.83 4.08 ± 0.63 4.00 ± 0.69 7.08 ± 0.88 6.24 ± 0.69 F(4,72) = 11.97, p < 0.001, partial eta2 = 0.4 Stage 2 (min) 44.37 ± 3.7 40.13 ± 3.30 46.28 ± 4.3 44.89 ± 2.6 44.10 ± 2.9 F(4,72) = 0.57, p < 0.67, partial eta2 = 0.03 SWS (min) 9.00 ± 2.7 23.07 ± 3.5 23.03 ± 4.9 18.87 ± 3.6 22.37 ± 4.1 F(4,72) = 4.36, p = 0.003, partial eta2 = 0.19 REM (min) 23.71 ± 3.2 24.05 ± 2.9 18.21 ± 2.5 14.61 ± 1.9 23.13 ± 2.9 F(4,72) = 2.68, p = 0.03, partial eta2 = 0.13 Placebo Sodium oxybate (2.5 g) Zolpidem (10 mg) Statistic TSTnap (min) 92 ± 3.2 91 ± 2.3 93 ± 1.3 F(2,58) = 0.08, p = 0.91, partial eta2= 0.003 Sleep latencynap (min) 9.2 ± 1.2 8.8 ± 0.94 10.5 ± 1.3 F(2,58) = 0.65, p = 0.52, partial eta2= 0.02 WASOnap (min) 17.7 ± 3.8 13.7 ± 2.4 13.8 ± 2.7 F(2,58) = 0.08, p = 0.91, partial eta2= 0.003 Sleep efficiencynap 78.9 ± 3.1 80.8 ± 2.2 80.5 ± 1.8 F(2,58) = 0.14, p = 0.86, partial eta2= 0.005 Stage 1 (min) 8.3 ± 0.87 6.1 ± 0.68 7.88 ± 0.95 F(2,58) = 2.26, p = 0.11, partial eta2= 0.07 Stage 2 (min) 43.6 ± 2.6 40.47 ± 2.88 39.2 ± 3.0 F(2,58) = 1.0, p = 0.34, partial eta2= 0.03 SWS (min) 9.8 ± 1.5 19.26 ± 3.0 24.3 ± 2.0 F(2,58) = 10.6, p < 0.001, partial eta2= 0.26 REM (min) 30.7 ± 2.3 25.9 ± 2.4 22.6 ± 2.4 F(2,58) = 4.55, p = 0.01, partial eta2= 0.13 Spindle feature Channel Placebo Sodium oxybate (2.5 g) Zolpidem (10 mg) Statistic Density C4 2.40 ± 0.14 1.68 ± 0.21 3.13 ± 0.24 F(2,58) = 19.64, p < 0.001, partial eta2 = 0.40 C3 2.78 ± 0.17 2.03 ± 0.25 3.45 ± 0.27 F(2,58) = 12.45, p < 0.001, partial eta2 = 0.30 Amplitude C4 16.96 ± 0.45 17.31 ± 0.46 16.43 ± 0.48 F(2,56) = 3.75, p = 0.03, partial eta2 = 0.11 C3 16.78 ± 0.52 17.01 ± 0.49 15.63 ± 0.44 F(2,56) = 7.39, p = 0.001, partial eta2 = 0.17 Frequency C4 13.58 ± 0.09 13.49 ± 0.09 13.49 ± 0.08 F(2,50) = 10.81, p < 0.001, partial eta2 = 0.20 C3 13.49 ± 0.10 13.48 ± 0.09 13.43 ± 0.09 F(2,56) = 1.33, p = 0.27, partial eta2 = 0.04 Fast spindle density C4 1.59 ± 0.23 1.23 ± 0.22 2.23 ± 0.27 F(2,52) = 10.81, p < 0.001, partial eta2 = 0.29 C3 1.85 ± 0.29 1.45 ± 0.25 2.40 ± 0.30 F(2,54) = 7.35, p = 0.002, partial eta2 = 0.21 Slow spindle density C4 0.77 ± 0.13 0.64 ± 0.11 1.46 ± 0.26 F(2,56) = 9.49, p < 0.001, partial eta2 = 0.25 C3 1.18 ± 0.22 0.80 ± 0.13 1.84 ± 0.39 F(2,52) = 5.46, p = 0.007, partial eta2 = 0.17 Fast spindle amplitude C4 16.34 ± 0.50 16.77 ± 0.48 15.88 ± 0.56 F(2,50) = 2.49, p = 0.09, partial eta2 = 0.09 C3 16.49 ± 0.68 16.32 ± 0.55 15.16 ± 0.50 F(2,54) = 2.74, p = 0.07, partial eta2 = 0.09 Slow spindle amplitude C4 17.20 ± 0.52 17.30 ± 0.43 16.66 ± 0.50 F(2,56) = 1.84, p = 0.168, partial eta2 = 0.06 C3 16.94 ± 0.52 17.28 ± 0.48 15.64 ± 0.42 F(2,56) = 10.36, p < 0.001, partial eta2 = 0.27 Placebo Sodium oxybate (2.5 g) Zolpidem (10 mg) A.M. P.M. A.M. P.M. A.M. P.M. Verbal memory: word-pair associates (number of correct pairs recalled out of 48 pairs) 24.5 ± 1.5 28.9 ± 1.3 26.7 ± 1.2 30.1 ± 1.0 24.1 ± 1.5 30.4 ± 1.0* Perceptual learning: texture discrimination (threshold in ms) 153.1 ± 16.9 133.4 ± 13.0 149.6 ± 16.4 132.1 ± 13.0 151.3 ± 17.0 163.4 ± 17.0* Motor learning: motor sequence (number of correct sequences) 20.0 ± 0.97 24.7 ± 1.0 21.5 ± 1.0 25.2 ± 1.1 20.8 ± 0.83 24.4 ± 0.91 ↵*p < 0.05.
