Study objectives: To investigate age and gender effects on the acute blood pressure (BP) and heart rate (HR) response to arousal from sleep in healthy adults.
Design: Healthy young and older male and female adults were aroused from stage 2 sleep throughout the night using an auditory tone. The magnitude of the cardiovascular responses to arousal were assessed using 2 (young v older) by 2 (male v female) ANOVAs with repeated measures over time.
Setting: Sleep laboratory at the Royal Brompton Hospital, London.
Patients or participants: 25 healthy young (< or = 40 years, n = 15 males) and 20 healthy older adults (> or = 60 years, n = 11 males).
Interventions: Arousals (> 10 seconds) from undisturbed stage 2 sleep were induced by an auditory tone throughout the night.
Measurements and results: Overnight polysomnography (PSG) with HR, continuous beat-by-beat arterial BP and respiratory measurements was performed. Older adults had smaller and delayed initial mean BP and HR responses to arousal compared to young adults (both P < 0.001), whereas changes in ventilation and tidal volume responses to arousal were similar between age groups (P = 0.3 and P = 0.6 respectively). There were no differences between females and males in the cardiovascular or respiratory responses to arousal from sleep.
Conclusion: The cause of the smaller and delayed response in healthy older adults is unknown; however, we speculate that for older people with sleep apnea, in whom nocturnal arousals occur frequently, the reduced cardiovascular response may be protective against the link between sleep apnea and hypertension.