Table 1. Differences in scalene and upper trapezius muscle activities among the three sleeping postures.

Muscle	Posture	Mean ± SD
Right scalene	BHS	1.00 ± 0.13
	BHC	1.04 ± 0.19
	DHF	1.41 ± 0.64*
Left scalene	BHS	1.00 ± 0.31
	BHC	1.05 ± 0.43
	DHF	1.12 ± 0.70
Right upper trapezius	BHS	0.93 ± 0.15
	BHC	0.93 ± 0.16
	DHF	1.92 ± 1.61*
Left upper trapezius	BHS	0.99 ± 0.09
	BHC	1.02 ± 0.85
	DHF	0.98 ± 0.64

BHS: both hands at the side in supine; BHC: both hands on the chest in supine; DHF: dominant hand on the forehead in supine; SD: standard deviation

*p<0.05 vs. BHS