The upcoming Moto 360 is expected to get a built-in ambient light sensor, but neither the LG G Watch or the Samsung Gear Live have one. That means that they cannot control their own brightness automatically depending on the environment — but there is a third-party app that can help.

Display Brightness for Android Wear uses your phone’s time and location to determine sunset times and just how bright or dark it may be, then adjusts the brightness of your watch’s display accordingly. It will also make adjustments depending on what you’re doing.

For instance, during the day when it’s bright, brightness will be set to medium if you’re still and not doing much, because it assumes you’re in doors. But it assumes you’re outdoors when you’re driving or on the move and raises the brightness to its highest levels. During the night, brightness will always be set to the lowest level.

It’s not completely perfect, of course, but it’s the closes you’ll get to automatic brightness controls on Android Wear devices without ambient light sensors. It saves you from having to make changes manually, or just leaving your watch on the highest brightness setting at all times and draining its battery life.

To install Display Brightness, simply download the app on your smartphone from Google Play by following the link below. You’ll only need to open it once and it will work in the background from then on.

• Google Play StoreDisplay Brightness