Table 3.
Sleep continuity, sleep architecture, and sleep-phase stability
| A/A (n = 39) | A/G (n = 14) | p value* | |
|---|---|---|---|
| Sleep continuity | |||
| Total sleep time | 402.73 ± 5.19 | 382.29 ± 11.92 | 0.07 |
| Sleep period time | 464.96 ± 2.59 | 449.79 ± 8.56 | 0.04 |
| Sleep efficiency (%)** | 86 ± 1 | 82 ± 2 | 0.11 |
| Sleep onset latency | 15.15 ± 2.18 | 29.75 ± 8.55 | 0.05 |
| All night sleep architecture | NS | ||
| NREM sleep | 311.00 ± 4.58 | 291.89 ± 10.20 | |
| SWS | 88.22 ± 4.67 | 87.29 ± 8.84 | |
| SWS latency | 12.72 ± 1.21 | 11.89 ± 1.31 | |
| Stage 1 sleep | 33.91 ± 3.11 | 35.14 ± 3.73 | |
| Stage 2 sleep | 222.78 ± 5.09 | 204.61 ± 8.77 | |
| Wakefulness | 25.40 ± 3.43 | 28.04 ± 6.43 | |
| REM sleep | 90.50 ± 3.87 | 89.25 ± 6.46 | |
| REM latency | 82.00 ± 6.51 | 94.50 ± 14.91 | |
| First sleep cycle architecture | NS | ||
| NREM sleep | 73.42 ± 5.50 | 78.32 ± 7.68 | |
| SWS | 40.51 ± 3.35 | 39.61 ± 4.90 | |
| Stage 1 sleep | 3.14 ± 0.46 | 7.82 ± 2.86 | |
| Stage 2 sleep | 32.91 ± 3.11 | 38.71 ± 4.68 | |
| Wakefulness | 2.21 ± 0.60 | 7.18 ± 4.41 | |
| REM sleep | 11.19 ± 1.12 | 14.68 ± 3.90 | |
| All night sleep-phase stability | NS | ||
| Number of entries into REM sleep | 13.87 ± 0.66 | 13.36 ± 1.90 | |
| Number of entries into NREM sleep | 25.62 ± 1.37 | 28.64 ± 2.75 | |
| Switches from stage 2 into stage 1/wake | 16.41 ± 1.28 | 21.07 ± 2.69 | |
| Switches from SWS into stage 1/wake | 2.74 ± 0.35 | 2.50 ± 0.45 | |
| First sleep cycle sleep-phase stability | |||
| Number of entries into REM sleep | 1.95 ± 0.16 | 2.50 ± 0.42 | 0.21 |
| Number of entries into NREM sleep | 3.41 ± 0.41 | 6.71 ± 1.37 | 0.01 |
| Switches from stage 2 into stage 1/wake | 2.05 ± 0.34 | 5.14 ± 1.26 | 0.01 |
| Switches from SWS into stage 1/wake | 1.05 ± 0.18 | 1.29 ± 0.27 | 0.29 |
Group mean ± SEM of sleep characteristics in minutes. MANOVA revealed a marginal effect of genotype on sleep continuity, which tended to be worse in subjects with A/G genotype (F(4,48) = 2.388, p = 0.06). MANOVA did not detect genotype differences in sleep architecture in the whole night as well as during the first sleep cycle. Also, MANOVA revealed significant lower sleep-phase stability in subjects with A/G genotype in the first sleep cycle (F(2,50) = 2.361, p = 0.047). The p values in bold type indicate statistical significance.
*In case of significant MANOVA outcome, two-tailed unpaired post hoc t test.
**Sleep efficiency is the ratio of sleep to time spent in bed shown as a percentage.