Objective sleep parameters
SE, sleepiness, ®
Patients wear an actimeter on their non-dominant wrist (ActiGraph® GT3X-BT, Pensacola, FL, USA) from bedtime until waking up, for seven consecutive nights. A sleep diary is used, as a complement to actigraphy, to determine when patients are awake and when they are lying down attempting to sleep. The sleep diary collects habits and sleep hygiene over an extended period of two weeks. Patients indicate bedtime, wake-up time, awakenings, periods of sleep and sleepiness, and consumption of drugs. In addition, the subjective quality of sleep and awakening are indicated.Data from actigraphy are downloaded and analyzed on ActiLife software (ActiGraph®, Pensacola, FL, USA). All records are scored as asleep unless the sleep diary indicates that the patient is lying in bed attempting to sleep. Data are downloaded and analyzed using the Cole-Kripke algorithm on ActiLife software in 60 s epochs. Once the bedtime and wake-up time are defined, automatic Cole-Kripke algorithm analyses are run to extract the following sleep parameters: bedtime (h:min), wake-up time (h:min), SOL (the first minute that the algorithm scores “asleep”), TIB, TST, WASO, awakenings (the number of different awakening episodes as scored by the algorithm), average awakening (the average length, in minutes, of all awakening episodes), total counts (the total actigraphy counts summed together for the entire sleep period), sleep efficiency (SE, number of sleep minutes divided by the total number of minutes the subject is in bed x 100: TST/TIB x 100).