The prevalence of irregular breathing during sleep is age and gender depend
ent, but the reason for this is unknown. This study tested the hypothesis t
hat older men have a greater sleep-related increase in respiratory resistan
ce. In 48 healthy subjects, 12 in each of four groups of younger and older
men and women, airway resistance was measured during wakefulness and sleep
using a mask, pneumotachograph, and catheter-mounted pressure sensors. Tota
l respiratory resistance and total "low-flow," and "high-flow" oropharyngea
l resistance were analyzed from 170,000 breaths, high flow being at rates a
bove 50% maximal inspiratory flow. High-flow oropharyngeal and total respir
atory resistance increased during nonrapid eye movement (NREM) sleep in all
groups but not low-flow resistance. Total respiratory resistance increased
from 12 +/- 1.2 cmH(2)O.l(-1).s(-1) awake to 16.2 +/- 2.4 in NREM sleep in
young men, from 22.8 +/- 3.6 to 33.6 +/- 5.4 in young women, from 18 +/- 3
to 34.8 +/- 4.8 in older men, and from 26.6. +/- 4.2 to 34.2 +/- 6 in olde
r women. The percentage of change in total respiratory resistance from awak
e to NREM sleep was not different between age groups or genders. We conclud
e that there are no major age or gender differences in the changes in airwa
y resistance with sleep in normal subjects.