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Actigraphy data are collected in MAP with an activity monitor. The specific actigraphy device has changed over time but the data collected by each device can emulate the original Actical signals in order to calculate the same actigraphy metrics for analyses.
The AX3 device (Axivity; Newcastle upon Tyne, UK) is a lightweight triaxial accelerometer that has a large block NAND flash memory chip linked by a USB enabled microcontroller. The waterproof device includes a temperature sensor, ambient light sensor, real time clock, and rechargeable lithium polymer power source.
Data is logged internally, at a sampling rate of 50 Hz, in a binary packed format called Continuous Wave Accelerometer (CWA) format. Upon retrieval of the device, the raw data is downloaded and viewed using the OMGUI software provided by Axivity. The software provides provision to convert the raw CWA files into either Comma Separated Value (CSV) or Multi track audio (WAV) format with variety data interpolation and timestamp formatting options.
The GENEActiv device (Activinsights Ltd.; Cambridgeshire, UK) is a lightweight triaxial accelerometer worn on the non-dominant wrist. The waterproof device measures activity, light, temperature, and includes a rechargeable lithium polymer battery.
Data is recorded in open format with timestamps. Upon retrieval of the device, raw data are downloaded and viewed using GENEActiv software. Activity counts can be convered to epochs of 1, 5, 10, 15, 30, or 60 seconds.
Actical (Philips Respironics; Bend, OR) is a compact, battery-operated activity monitor similar in size to a wristwatch and worn on the non-dominant wrist. The waterproof device uses a piezoelectric triaxial accelerometer to monitor the occurrence and degree of motion. This type of sensor and the associated digital integration signal processing considers both degree and intensity of motion to produce an electrical current that varies in magnitude. An increased degree of speed and motion produces an increase in voltage, which is stored by the device as 1-second sample activity counts. Upon retrieval of the actigraph, raw data are downloaded and viewed using software provided by Respironics, Inc. to confirm if recording failures occurred. Activity counts are then summed over 15-second internals (epochs).
Raw actigraphy data are available, subject to committee review.
See the Sleep and Circadian Rhythm category for measures of sleep.
|Average total daily activity||Actical activity measure - Average total daily activity (MAP only)|
|Average daily activity per active hour||Actical activity measure - Average activity per hour of activity (MAP only)|
|Average daily inactivity||Actical activity measure - Average percentage of day without activity (MAP only)|
|Transition probability - Activity to rest||From Sleep and Circadian Rhythms|
|Transition probability - Rest to activity||From Sleep and Circadian Rhythms|
|Interdaily stability||From Sleep and Circadian Rhythms|
|Interdaily variability||From Sleep and Circadian Rhythms|