DIURNAL RHYTHM OF PLASMA DELTA-SLEEP-INDUCING PEPTIDE IN HUMANS - EVIDENCE FOR POSITIVE CORRELATION WITH BODY-TEMPERATURE AND NEGATIVE CORRELATION WITH RAPID EYE-MOVEMENT AND SLOW-WAVE SLEEP
Tc. Friedman et al., DIURNAL RHYTHM OF PLASMA DELTA-SLEEP-INDUCING PEPTIDE IN HUMANS - EVIDENCE FOR POSITIVE CORRELATION WITH BODY-TEMPERATURE AND NEGATIVE CORRELATION WITH RAPID EYE-MOVEMENT AND SLOW-WAVE SLEEP, The Journal of clinical endocrinology and metabolism, 78(5), 1994, pp. 1085-1089
Since delta-sleep-inducing peptide (DSIP) was isolated in 1977, numero
us reports have suggested that this nonapeptide stimulates asleep [slo
w wave sleep (SWS)]. Although DSIP-like immunoreactivity (DSIP-LI) has
been found in the serum of many animals and man, its diurnal rhythm a
nd relation to sleep stages have not been well defined. We hypothesize
d that circulating levels of this putative sleep hormone would be high
est at night and would probably be elevated before or during episodes
of SWS. We, therefore, measured plasma DSIP-LI levels every 30 min for
24 h in 12 normal volunteers in whom we obtained simultaneous polygra
phic recordings. We found a distinct diurnal rhythm for plasma DSIP-LI
levels, with the maximum at 1500 and the minimum at 0100 h. DSIP-LI l
evels were substantially lower in rapid eye movement sleep (P < 0.005)
and somewhat lower in SWS (P < 0.05) compared to awake values. DSIP-L
I levels did not rise before, during, or after a significant percentag
e of episodes of SWS. We found, however, that the diurnal rhythm of DS
IP-LI closely followed that of body temperature with a high degree of
correlation (r(2) = 0.66; P < 0.0001). We conclude that endogenous ele
vations of circulating DSIP may be associated with suppression of slow
wave and rapid eye movement sleep, and that the circadian rhythm of t
his peptide is coupled directly or indirectly to that of body temperat
ure.