What is actigraphy?
Actigraphs are accelerometer-based devices that have been used to evaluate sleep and wake cyles in humans for nearly four decades. These come in the form of compact, lightweight, typically wrist-worn devices that may look like simple wrist-watch at first 1. Although polysomnography (PSG) continues to be the gold standard for sleep assessments, actigraphs are an attractive because of their ease of use, lower associated expenses, and the possibility to record continuous data over multiple days and in a subject’s home environment 1.
What considerations should be made when purchasing an actigraph?
| Spec | Considerations |
|---|---|
| Accelerometer | Always purchase an omnidirectional or triaxial accelerometer, with the ability to record in 30-second or 1 minute epochs. Flexible data collection parameters (e.g. epoch length) are a plus) |
| Appearance | To consider. Bulky or heavy devices might be associated with less adherence to your study protocol |
| Event markers | Also called “event logging”. A useful plus! These can come in the form of a button that a subject needs to press to signal a specific event. |
| Light sensors | Also recommended. If embedded in the device, these can help identify bed and wake times. |
| Battery type | Whether rechargeable or disposable, the battery needs to be able to record a minium of 3 days. Ideally, it should record up to 2 weeks of data. |
| Data storage and memory | Nonvolatile memory that allows information to be stored even if the battery fails is recommended. Make sure you don’t lose data. |
| Data access | I always require access to the raw data and prefer open-source tools when it comes to software. |
| User support | When you run into issues with the device or software, you will probably want to talk to a human. What is the user support like? |
What is out there?
| Name 📇 | Company 🏛️ | Sensors 👋 | Battery time 🪫 | Raw data 💾 | Free trial? 💸 | Other considerations 🔮 |
|---|---|---|---|---|---|---|
| GENEactiv Original | Activinsights | 👋, 🔦, near-body 🌡️ | 45 days @ 10Hz; 7 days @ 100Hz | .bin & .csv | Yes | Open-source software. Event logging. Analysis services are offered separately. Large list of publications. Waterproof. 1-year warranty. |
| ActiGraph wGT3X-BT | ActiGraph | 👋, 🔦 | 25 days (wireless disabled, 30 Hz sample rate) | .csv & .xlsx | ╳ | No event logging. Not waterproof (should be removed if the participant goes swimming). Uses zero-crossing mode (not recommented). Other products (without 🔦 sensors) from Actigraph can be viewed here |
| Everion | Biofourmis | 👋, 🌡️, electrodermal activity, photoplethysmography | ~32 hours | ? | .json | Worn on arm instead of wrist. |
| Readiband | Fatigue Science | 👋, 🌡️, (wrist and ambient), 🔦 | >2 months (60s epoch) | .txt | ? | Event logging. |
| Move 4 | Movisens | 👋, 🌡️ | ~ 7 days | unisens | Yes | Wear locations: Hip, Chest, Wrist, Upper Arm, Ankle, Thigh. Software license valid for one computer. |
| LightMove 4 | Movisens | 👋, 🌡️, 🔦 | ~ 7 days | unisens | Yes | Wear locations: Wrist. Software license valid for one computer. |
| Actiwatch Spectrum Plus & Pro | Philips | 👋, 🔦 | 50-60 days (1 min epochs) | ╳ | Yes | Very expensive. Waterproof. Event logging. |
| Motion Watch | Camntech | 👋, 🔦 | 22 days @ 15 sec epoch | .csv | Yes | Waterproof. Can be used in contact sports. Event logging. Offer support via phone/email. 2-year warranty. Paid software with limited user license. |
Legend:
- 👋: motion
- 🔦: light
- 🌡️: temperature
Closing remarks
I have definitely not used all of these devices myself and would be curious to hear thoughts from others who have! If I failed to list a device which should definitely be in this list, let me know!