shows the frequency of the four sle

shows the frequency of the four sleep positions by the 40
participants. The frequencies of sleep in the supine, left lateral, right
lateral, and prone positions were 481, 244, 221, and 22, which
occupied 49.7, 25.2, 22.8, and 2.3 percent of the total frequency,
respectively. The frequency in the supine position was the greatest,
whereas that in the prone position was the lowest. The sum of
frequencies in the left lateral and right lateral positions was 465
sleep episodes, which was approximately equivalent to the frequency
in the supine position (465/481 ¼ 96.7%). This result indicated
that both the supine and lateral positions were significantly
important during sleep. The mean frequencies of sleep in the supine,
left lateral, right lateral, and prone positions of one subjects
one night were 12.03, 6.10, 5.53, and 0.55 times, respectively. The
total rotation frequency was 24.2 times (SD ¼ 7.99 times) for a
person a night (Table 2). The minimum rotation frequency was only
eight times and the maximum was 48 times.