Table 1.
Summary of physiological responses and variables from actigraphy
| Variables | No warming (CON) | Feet warming | P value |
|---|---|---|---|
| Sleep-onset latency [min] | 16.0 ± 7.9 | 8.5 ± 7.8 | 0.018 |
| Sleep efficiency [%] | 86.2 ± 5.1 | 93.8 ± 5.1 | 0.047 |
| Total sleep time [min] | 362.0 ± 21.4 | 394.0 ± 21.6 | 0.047 |
| Number of awakenings [times] | 16.3 ± 4.9 | 8.8 ± 4.3 | 0.041 |
| Total counts [times] | 14,314 ± 3303 | 7926 ± 5497 | 0.056 |
| Wake after sleep onset [min] | 42.0 ± 20.4 | 17.5 ± 14.5 | 0.078 |
| Average awakening length [min] | 2.5 ± 1.0 | 1.8 ± 1.1 | 0.345 |
| Movement index (MI)a [%] | 14.52 ± 2.55 | 9.09 ± 5.20 | 0.079 |
| Fragmentation index (FI)b [%] | 11.07 ± 7.72 | 5.36 ± 9.41 | 0.328 |
| Sleep fragmentation index (SFI)c [%] | 25.59 ± 10.09 | 14.45 ± 9.36 | 0.134 |
| Decreases in rectal temperature for 7-h sleep [°C] | 0.63 ± 0.39 | 0.54 ± 0.31 | 0.427 |
| Averaged mean skin temperature for 7-h sleep [°C] | 35.1 ± 0.2 | 35.2 ± 0.3 | 0.660 |
| Averaged distal-proximal skin temperature gradient (DPG) for 7-h sleep [°C] | − 0.78 ± 0.56 | − 0.19 ± 0.50 | 0.043 |
| Insensible body mass loss for 7-h sleep [g h−1] | 42.4 ± 16.7 | 52.6 ± 10.3 | 0.280 |
| Increases in ankle skin temperature at 2.5 h [°C] | 3.7 ± 2.6 | 4.8 ± 2.9 | 0.547 |
| Averaged ankle skin temperature for 7-h sleep [°C] | 33.6 ± 0.6 | 34.3 ± 0.4 | 0.003 |
| Averaged foot skin temperature for 7-h sleep [°C] | 34.2 ± 0.4 | 35.0 ± 0.2 | 0.012 |
| Averaged hand skin temperature for 7-h sleep [°C] | 34.4 ± 1.0 | 34.8 ± 0.7 | 0.287 |
| Averaged heart rate [bpm] | 61 ± 7 | 63 ± 6 | 0.245 |
All data were expressed as mean ± SD
aMI the percentage of periods with positive value in the y-axis counts during the sleep period
bFI the percentage of 1 min periods of sleep versus the whole periods of sleep
cSFI the sum of MI and FI (N = 6 except for the foot temperature [n = 5])