Effects of feet warming using bed socks on sleep quality and thermoregulatory responses in a cool environment

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])

ISSN: 1880-6805