Actigraphy data from four representative patients. Each panel shows intensity of activity across each recording day. Red lines indicate the fit of the circadian rhythm. Note the periodic structure of the activity of the two patients with significant rhythms (left), compared with those without (right). Patients 19, 21, 52 and 45 are shown (clockwise from top-left). Log activity data smoothed across five minutes is plotted for clarity of visualization.