This graph shows the hourly distribution of sleep for each day of the week. It includes both night sleeps and naps. It gives a general idea of what times a person is normally asleep during each day of the week.
The specific example below shows the sleep habits of a person between March 15th and April 4th. This person seems to go to sleep later than usual Thursday-Saturday and earlier than usual on Sunday night. The person seems to wake up between 10am and 11am most days and takes a nap in the afternoon a few times a week.
This is a relatively simple graph where a variably sized green ball appears at each hour interval for each day of the week. The size of the green balls is important where:
Notice that in the above example, the small green balls for the 7am hour on Wednesday and Friday seem strangely out of place between big green balls on either side. This is indicative of a hole occurring frequently during this time. It can happen on these days if, for example, one ends up waking up to take out the trash on these days and then returns to bed for a few hours.
Also note that all the green balls on Sunday of the above graph appear smaller relative to other days. This might be indicative of skipping sleep altogether on a particular Saturday night and Sunday morning during the computational period. Because of the short 3 week computational period in this example, one such event can have a significant impact whereas if the period was longer, it would naturally have less of an effect which would result in comparably sized balls unless the skipping of sleep entirely on a particular day is a more regular occurrence. This skipping of sleep might be a contributing factor to the early bedtime on Sunday night shown on the graph also.