Sleep and Physical Activity Validation Sub-study


What is the purpose of this study?

The purpose of this research is to understand the performance of sleep and physical activity measurement tools, including a Fitbit device and a smartphone application, Beiwe.

What is expected of me during this study?

You will be asked to:

  • Complete a short online questionnaire on your sleep habits.
  • Wear an NHS3-provided Fitbit and Actisleep watch on the same wrist for 14 consecutive days, including while you sleep.
  • Share your Fitbit data via Fitabase, an online platform that delivers your sleep data to our research team.
  • Answer a 5-minute sleep questionnaire each morning via the Beiwe app.


What is Beiwe?

The Beiwe smartphone app is a data collection platform for iOS and Android devices that collects movement data that can be used to measure sleep and physical activity. It was developed by the Onnela lab at the Harvard T.H. Chan School of Public Health.


Will Beiwe use my cellular data or drain my phone battery?

No. The smartphone application will rely on WiFi to upload data collected during the study. Data usage of the smartphone application is minimal (~10 MB per day). Please be sure to connect to WiFi at least once per week so the application can backup your data, though we recommend connecting once per day. The app has been designed to have a minimal impact on your phone’s battery life..


What data is collected via Beiwe?

Beiwe surveys will ask you questions about your daily sleep. The smartphone application will use the sensors on your smartphone to collect information on accelerometry (movement) when your phone is on or off.


Do I need to keep my phone with me during the study?

Yes, please try your best to keep your phone with you at all times during the study to provide us with the most accurate data. This could be in your pocket or in a bag/backpack during waking hours and in your home at night.


I forgot to answer my morning questionnaire. What should I do?

If you forget to fill out the Beiwe questionnaire when you wake up, please complete it as soon as you remember.


I got a notification that I have a survey to answer, but when I open the app, there is no survey available.

Please click on the notification that pops up on your phone to access the surveys. The notification will take you directly to the survey in the app.


My screen is going blank when I try to open the Beiwe app.

This is a known bug. This issue usually resolves itself if you exit out of the app and reopen it a few minutes later. For any other technical issues, please contact the study staff at



Can I use my own Fitbit if I already own one?

Please use the NHS3-provided Fitbit during the study period. If you also wear a personal Fitbit device, you may wear it in addition to the NHS3-provided Fitbit.


What Fitbit model is provided in this study?

Fitbit Charge 3.


Can I use the Fitbit after the study is over?

You are free to use the Fitbit however you like after the study ends.


When will I need to wear the Fitbit?

You will need to wear the NHS3 Fitbit for 14 days, 24 hours a day (you may take it off to bathe or swim).


Should I change my sleep/physical activity routine during the sampling period?

No, there is no need to change your sleep or physical activity during the study period. The long-term goals of the research are to learn how various measurement tools perform compared to research-grade accelerometers (Actisleeps).


Is this study sponsored by Fitbit?

No, this study is not sponsored by Fitbit. We are using Fitbit devices to measure sleep, heart rate, and activity, but we are neither supported by nor partnering with Fitbit.


Can I look at all my sleep/exercise data during the study period?

You are free to interact with the Fitbit device and the Fitbit app during and after the study.


What happens if I lose or break my Fitbit?

Please contact the study team at


I lost my instructions. Where can I get a new copy?

Please contact the study team at


When should I charge my Fitbit?

Because sleep is the focus of this research, we ask that you charge your Fitbit when you are NOT sleeping. You should charge your Fitbit fully before starting the study. Battery life is typically between 3-5 days, depending on usage and other factors, and a full charge will take 1-2 hours. Please keep your Fitbit charged, as a low battery will negatively affect data quality.


Should I start the study if I expect to travel in the next 14 days?

If you are going to travel (especially between time zones), we ask that you wait to begin the study until you complete your travel. If you have just returned from traveling between time zones, please wait until you have readjusted to your current time-zone to begin the study.


Will the Fitbit use my cellular data?

Syncing the Fitbit device to the Fitbit app will use a small amount of data.

For Fitbit Charge 5, approximately 50MB of data may be used over the 14-day study period.


How is my Fitbit data collected and stored?

Your Fitbit account data will be collected through Fitabase, a secure research platform. Your privacy is important to us. All Fitbit account data is encrypted while stored on the phone, awaiting upload, and in transit.


How can I ensure data collection is stopped after the 14-day study period?

Fitabase will automatically stop data collection from your Fitbit account after 28 days. At the end of the 14-day study period, you may elect to manually unlink your Fitbit account from Fitabase.


Research-grade accelerometer (Actisleep)

How can I ensure data collection is stopped after the 14-day study period?

The Actisleep does not have an on/off switch. It will begin data collection as soon as you put it on.


Do I need to charge the Actisleep?

No, you will not need to charge the device during the study period.


Do I need to return the Actisleep?

Yes. After the study period is over, we will ask you to use a prepaid shipping label provided to you to ship the Actisleep back to NHS3.