Two related studies are reported. Both involved the use of wrist actim
etry and morning sleep logs in subjects 23-67 years of age. In the fir
st study, 46 pairs of bed partners were monitored for 8 nights to asse
ss the extent and concordance of their body movements, and whether the
latter exhibited age and gender differences. The second study concent
rated on the presence or absence of a bed partner, and included subjec
ts who either habitually slept alone or whose usual partner was absent
for at least 1 night. Men showed a significantly greater number of di
screte movements during sleep than did women. Overall, 5-6% of all 30-
second sleep epochs contained such movements, with about 1/3 of these
movements being common (within the same epoch) to both partners. This
concordance was highest in younger couples. Female bed partners report
ed being disturbed more often by their partner than was the case for m
ale partners. Subjects sleeping with a partner showed a greater number
of discrete movements than matched subjects who slept alone. Movement
s decreased during temporary absence of the usual bed partner. Couples
seemed unaware of the similarity in the timing of their movements dur
ing sleep, and most reported sleeping better when their bed partner wa
s present.