The cardiovascular response to arousal from sleep decreases with age in healthy adults

To investigate age and gender effects on the acute blood pressure (BP) and heart rate (HR) response to arousal from sleep in healthy adults.

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.

Sleep laboratory at the Royal Brompton Hospital, London.

25 healthy young (< or = 40 years, n = 15 males) and 20 healthy older adults (> or = 60 years, n = 11 males).

Arousals (> 10 seconds) from undisturbed stage 2 sleep were induced by an auditory tone throughout the night.

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.

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.