Can the sleep estimation algorithms in the analysis software package be used to investigate daytime sleepiness?
The sleep estimation algorithms in our software were validated for estimating sleep in a standard sleeping environment. They have not been validated for naps or “micro-sleeps”, which can take place during the course of the day. The problem with actigraphic estimates of sleep is that one is dealing with a single channel of simple information. It is impossible for the actigraph to distinguish between periods of extreme inactivity (reading, TV watching) and sleep during the course of the day. What makes the nighttime estimates of sleep possible is the assumption that sleep is the intent during that period of time (based on event markings, logs, etc.). With knowledge that the subject is in bed and TRYING to sleep, the estimates of sleep from activity can be used with much more confidence. This does not mean that the actigraph cannot be used to examine daytime sleepiness; but one cannot say, with any certainty, that an inactive period is asleep. Solution? Don’t report these periods as naps.
