Skin surface blood flow at the fingertips was measured in a 21-year-old wom
an during sleep using laser Doppler flowmetry. Skin blood flow responses (S
BFR) are transient reductions in skin blood flow of about 25 s in duration.
In our subject, SBFR showed a delay time of 8-9 s from the onset of skin p
otential responses (SPR) and appeared more consistently than SPR. The frequ
ency of SBFR decreased during non-rapid eye movement sleep, especially when
the sleep stage became deep. These findings indicate the validity of SBFR
as a discrete index of autonomic function during sleep.