Normal sleep pattern analyzed statistically and studied by color "dormograms"

Polygraphic sleep recordings were made from 46 healthy adult volunteers during 159 nights and evaluated visually. Sleep stages for each 30 sec epoch were entered into a computer data base from which plots of individual nights, as well as color "dormograms" and/or statistical parameters for a set of nights, could be produced. The total mean dormogram in which all the nights were synchronized at sleep onset revealed a dominant sleep pattern, which was found to be very stable even for subgroups. Synchronizing at the beginning of the second REM period allowed the pattern for the last half of the nights to appear more clearly. A large number of different sleep parameters were calculated for each night and statistically analyzed. On the basis of these results a normal "mean" sleep pattern could be reconstructed and related to other studies of normal sleep patterns.