Sympathetic neural responses to 24-hour sleep deprivation in humans: sex differences

Abstract

Sleep deprivation has been linked to hypertension, and recent evidence suggests that associations between short sleep duration and hypertension are stronger in women. In the present study we hypothesized that 24 h of total sleep deprivation (TSD) would elicit an augmented pressor and sympathetic neural response in women compared with men. Resting heart rate (HR), blood pressure (BP), and muscle sympathetic nerve activity (MSNA) were measured in 30 healthy subjects (age, 22 ± 1; 15 men and 15 women). Relations between spontaneous fluctuations of diastolic arterial pressure and MSNA were used to assess sympathetic baroreflex function. Subjects were studied twice, once after normal sleep and once after TSD (randomized, crossover design). TSD elicited similar increases in systolic, diastolic, and mean BP in men and women (time, P < 0.05; time × sex, P > 0.05). TSD reduced MSNA in men (25 ± 2 to 16 ± 3 bursts/100 heart beats; P = 0.02), but not women. TSD did not alter spontaneous sympathetic or cardiovagal baroreflex sensitivities in either sex. However, TSD shifted the spontaneous sympathetic baroreflex operating point downward and rightward in men only. TSD reduced testosterone in men, and these changes were correlated to changes in resting MSNA (r = 0.59; P = 0.04). Resting HR, respiratory rate, and estradiol were not altered by TSD in either sex. In conclusion, TSD-induced hypertension occurs in both sexes, but only men demonstrate altered resting MSNA. The sex differences in MSNA are associated with sex differences in sympathetic baroreflex function (i.e., operating point) and testosterone. These findings may help explain why associations between sleep deprivation and hypertension appear to be sex dependent.

Sex and race differences in caloric intake during sleep restriction in healthy adults

“…Given the sex differences we observed, and that estradiol administration has an anorexigenic effect in rodents (37), future studies should assess how SR affects the menstrual cycle and estrogen concentrations and examine if this relates to changes in food intake. Sleep also influences testosterone concentrations; plasma concentrations peak during sleep (a sleep-dependent effect), and experimental sleep deprivation decreases testosterone concentrations in men (39)(40)(41). Decreased testosterone concentrations have been associated with increased adiposity, but to our knowledge, no studies have examined the effect of androgens on food intake in humans (37).…”

Testosterone induces apoptosis in vascular smooth muscle cells via extrinsic apoptotic pathway with mitochondria-generated reactive oxygen species involvement

“…However, reports of sudden cardiovascular death among male athletes abusing of anabolic steroids and the fact that in many experimental models of hypertension [spontaneously hypertensive rats (54), Dahl salt-sensitive rats (13), genetically hypertensive rats (1), and rats with deoxycorticosterone acetate-saltinduced hypertension (15)], males have higher levels of arterial pressure, which are abrogated by orchiectomy (9,54), indicate that testosterone is detrimental to the cardiovascular system. In addition, testosterone has been shown to directly affect many of the mechanisms that control cardiovascular function, such as the renin-angiotensin-aldosterone system, sympathetic neural activity, endothelial function, and VSMC tone (7,14,40). Finally, it is important to mention that findings from preclinical studies often differ from those in the clinical setting and therefore should be cautiously interpreted.…”

Sleep efficiency and nocturnal hemodynamic dipping in young, normotensive adults

“…Subjects wore a wrist actigraph watch (Actiwatch-64; Mini Mitter, Philips Respironics, Bend, OR) for a total of 7 days and nights over the course of ϳ1 mo. The actigraphy data were used to ensure adequate sleep time for another study (9). As such, actigraphy was recorded for 3 or 4 consecutive nights, ϳ1 mo apart; all female subjects were studied during the early follicular phase of both months.…”