The effect of gender on autonomic and respiratory responses during sleep among both young and middle-aged subjects.

BACKGROUND AND OBJECTIVES: Sleep affects the control of circulation and respiratory function. Gender and age are also known to have a profound impact on the neural control of circulation. We investigated whether gender affects sleep-related cardiovascular and respiratory responses and whether these vary according to healthy subjects being young or middle-aged. METHODS: We studied 32 subjects: 8 women and 8 men aged 20-30 years (young), and 8 women and 8 men aged 50-60 years (middle-aged). Young women were under oral contraceptive therapy and middle-aged women were postmenopausal and not receiving hormonal replacement therapy. One-night polysomnography was used to assess RR variability during non-rapid eye movement (NREM) (stage 2) and rapid eye movement (REM) sleep. Low-frequency (LF) and high-frequency (HF) components, in normalized units (LFnu and HFnu) and LF/HF ratio were calculated on five-minute segments selected across the night and averaged for each sleep stage. The respiration frequency in NREM and REM sleep was also measured. Interaction between gender, age and sleep on autonomic and respiration variables was assessed by 2 x 2 x 2 analysis of variance (ANOVA). RESULTS: Compared to men, women had a greater NREM-to-REM increment in LFnu (gender-by-state interaction, p<0.01), a greater decrement in HFnu (interaction, p<0.01) and a greater increment in LF/HF (interaction, p<0.05). Women also showed a more pronounced increase in respiratory frequency during REM sleep compared to men in both groups of age (gender-by-state interaction, F=7.1, p<0.05). No gender-by-age-by-state interaction was observed to affect autonomic and respiration variables. CONCLUSION: NREM-to-REM excitatory cardiac and respiratory responses are more marked among women compared to men, regardless of their hormonal status and whether they are young or middle-aged.

Age-at-onset in restless legs syndrome: a clinical and polysomnographic study.

OBJECTIVE: To determine the distribution of age-at-onset in a large cohort of patients with restless legs syndrome (RLS) and to compare clinical and polysomnographic characteristics of patients with early and late age-at-onset of RLS. METHODS: Two hundred and fifty patients with RLS were studied. Information on age-at-onset, etiology, familial history and symptoms severity of RLS was obtained. Age-at-onset density functions were determined from bootstrap methods and kernel density estimators. RESULTS: Age-at-onset showed a significant bimodal distribution with a large peak occurring at 20 years of age and a smaller peak in the mid-40s. Early- and late-onset RLS could be separated with a cut-off at 36 years of age. Distributions of age-at-onset differed as a function of presence/absence of a familial history and etiology of RLS. Age-at-onset clearly differentiated patients with a primary RLS (early onset) from those with secondary RLS. Finally, early-onset RLS was associated with increased RLS severity with higher indices of periodic leg movements in sleep (PLMS) associated with microarousals and periodic leg movements during wakefulness (PLMW). CONCLUSIONS: Early- and late-onset RLS could be distinguished depending on familial history and etiology of RLS. Our data suggest that different pathological processes are involved in these two groups, the early-onset group being highly genetically determined.

Nocturnal blood pressure changes in patients with restless legs syndrome.

OBJECTIVES: To assess heart rate (HR) and blood pressure (BP) changes associated with periodic leg movements during sleep (PLMS) with or without EEG signs of arousal in subjects with primary restless legs syndrome (RLS). METHODS: Ten patients with RLS (4 women, aged 47.3 +/- 13.5 years) underwent one night of polysomnography along with noninvasive beat-to-beat BP monitoring. Ten PLMS with microarousals (PLMS-MA) and 10 PLMS without microarousals (PLMS-noMA) were analyzed in each subject. Systolic and diastolic BP (SBP, DBP) were measured within a 25-beat temporal window comprising 10 beats before and 15 beats after onset of each movement. PLMS-related BP changes were assessed by repeated measures one-way analysis of variance. BP changes associated with PLMS-MA and PLMS-noMA were compared by paired t-tests. Pearson correlation coefficients were used to assess the relationship between cardiovascular changes and clinical and polysomnographic variables. RESULTS: BP increased significantly in association with all PLMS (on average, SBP 22 mm Hg, DBP 11 mm Hg). BP changes associated with PLMS-MA were greater vs those associated with PLMS-noMA (p < 0.05). SBP and DBP changes increased with age and the duration of illness. CONCLUSIONS: Periodic leg movements-related repetitive nocturnal blood pressure fluctuations could contribute to the risk of cardiovascular diseases in patients with restless legs syndrome, especially in the elderly.