Support Center

Lux Measurements

Last Updated: Nov 28, 2016 01:45PM CST

Lux, or ambient light, is measured by ActiGraph’s ActiSleep, ActiSleep+, ActiTrainer, GT3X+, and our new wireless wGT3X+ and wActiSleep+ devices. Ambient light may affect subject sleeping habits and thus is a useful tool in analyzing circadian rhythms and sleeping patterns. Lux data is stored once per epoch. For GT3X+/ActiSleep+/wGT3X+/wActiSleep+ devices, Lux data is stored once per second. When converting a GT3X+ raw file into an accumulated *.agd format with epoch lengths greater than one second, the lux values for that epoch are averaged. 

The ActiTrainer, GT3X+, and wGT3X+ devices are capped at a maximum value of 2500; the ActiSleep, ActiSleep+, and wActiSleep+ are capped at 6000:

The wGT3X-BT device is capped at a maximum lux value of 5000 and the wActiSleep-BT is capped at 6500. The new GT9X Link device does not have a lux sensor.

An estimate of industry accepted lux values is shown below:

 

    Lux Level                          Interpretation Comparison

1
Twilight
5
Minimal Street Lighting
10
Sunset
50
Family Living Room
80
Hallway 
100
Very Dark Overcast Day 
320 - 500
Office Lighting 
400
Sunrise/Sunset 
1,000
Overcast Day 
10,000-25,000
Full Daylight 
32,000-130,000
Direct Sunlight 

 

Note that these levels are only estimates and are not meant for exact interpretation of the light detected by the device. Lux values reported by ActiGraph devices are only intended as a general guideline for average light intensities.

You can also refer to the attached Data Sheet for more information.

Please also refer to the following Wikipedia page for more information on Lux values:

http://en.wikipedia.org/wiki/Lux

If you need any further assistance, please go to our support portal at https://help.theactigraph.com/home. From here, you can view many helpful FAQ's and Troubleshooting Articles; log in to check any existing Support Requests; or create a new Support Ticket if you are unable to find a solution. You can also email us at support@theactigraph.com or give us a call at (877) 497-6996, Monday through Friday, 8 am to 5 pm CST.

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