Abstract
To evaluate the influence of elevated back part of beds (back angles to the horizontal of 0, 10, 20 and 30 degrees), we estimated subjective sleep quality and measured objective sleep variables by sheet-shaped body vibrometer which is placed under a mattress or a futon and can produce almost identical sleep/wake scores to wrist actigraphy. Thirteen healthy male subjects, aged 24–42 (mean 29.2), spent one night sleeping at home in each of the four back angles in random order. Sleep in back angles of 20 and 30 degrees resulted in poor subjective sleep quality and reduced sleep efficiency. These results suggest that back angles of 20 degrees or more decrease sleep quality and back angles of 10 degrees or less have little influence on sleep.
