​An actigraphy is used to measure movement activity over the course of several days. An actigraph is a small, watch-like measurement device that is attached to the wrist with a strap. The device is removed during showering but otherwise it is kept on the wrist for the entire duration of the examination, during the day and night.

During the examination, the patient can go about his or her normal everyday routines and follow his or her daily schedule. When going to bed and waking up, the button on the actigraph is pressed and these times are also marked in a sleep diary. There are no contraindications for the examination, but careful adherence to the instructions is crucial for the success of the study.

The actigraph measures movement with the help of a sensitive acceleration sensor. A value describing the amount of movement is saved in the memory of the device every 60 seconds. The results can be used to draw conclusions on the length and calmness of the sleep period and the timing and regularity of the sleep-wake pattern.

In many cases, an actigraphy examination is performed in connection with a multiple sleep latency test (link) and it takes 3 to 7 days. It can also be performed as a separate examination, lasting 2 to 3 weeks. This provides more accurate information regarding the permanence of the sleep-wake pattern and the division of daytime activity.