 
 HELP WITH THE ACTIGRAPH
This small device is used to measure activity and light. It is already turned on, and recording. It will keep recording until you send it back to us. Please strap the device on your non-dominant wrist (that’s your left if you are right-handed). Since it is water resistant, you never have to take it off.
If you have any questions, see the answers below. If you still have questions, you may call the study coordinator at (215) 615-1756 or email them for more information.
Q: How do I put it on?
A: Strap it on to your wrist, like a wristwatch. Make sure you keep it on your non-dominant wrist. If you are right-handed, keep it on your left wrist, and if you are left handed, keep it on your right wrist. You should make sure that, like a wristwatch, it is tight enough to stay on your wrist, but loose enough to be comfortable.
Q: When should I take it off?
A: It is very important that you wear this device all day and all night. You should not take it off at all until you are finished wearing it. If you do ever take it off, you should put it back on as soon as possible. It is OK if you go swimming or surfing. It is OK if you take a bath or shower. It is OK to keep it on while you wash your hands or do dishes. It is also OK to leave it on while you play sports or do other physical work. They can be bumped around quite a bit without becoming damaged.
Q: How does it work?
A: This small device measures activity and light. It measures activity with a small accelerometer. Any tiny movement, in any direction, will be recorded with the device. It cannot tell what type of movement it is, only how much. That way, we can use this device to measure when you are asleep and when you are awake across 24 hours. Even though we only measure activity from your wrist, these measurements correspond to the rest of your body as well (example: try walking while keeping your wrist perfectly still). It measures light using a small photometer. The small circle on the outside of the device is like a small eye, measuring how bright the light it. It is not a camera – it only records the brightness of light.
Q: Do I get to keep it?
A: No. We trust you will return the device at the end of the study. Without the right equipment and training to run and read it, this device is not useful. We insist that you return the device at the end of the study. If you lose it, or if you insist on keeping it, we may need to charge you for the cost of a new one to replace it.
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University of Arizona