Does your head hurt?Do you suffer at night to sleep?Believe it or not, your cell phone may be to blame.Scientists believe that a certain frequency in the light emitted by electronic devices contributes to these problems.Fortunately, there are easy ways to remove them.We explain how to enable the blue light filter on your phone – whether you have an iPhone or Android device – so you can rest better.The Night Shift feature in iOS allows you to filter out blue light and adjust the warmth of colors on your screen.Automatically adjust them when the sun sets in your location, using geolocation and your cell phone's clock to determine it.When it is morning, the screen returns to its usual configuration.You can activate Night Shift by opening Control Center and pressing Brightness Control.Then tap on the symbol that looks like a small sun.Alternatively, go to Settings > Display & Brightness > Night Shift.We recommend adjusting the Night Shift setting when you turn on Scheduling and enter times for it to turn on and off automatically.Ours is from 10 pm to 7 am If you don't set a time, it will turn on at sunset and turn off at sunrise.You can also manually enable it until the next day.Most Samsung Galaxy phones, like the new S21, now have a blue light filter option.The quickest way to turn it on is to pull down the notification shade and swipe down again to access quick settings.One of them is called Blue Light Filter, and you can tap on it to turn it on and off.Also look under Settings > Display > Blue Light Filter.You can adjust the opacity with a slider and also tap Turn on as scheduled and then choose Sunset to Sunrise or Custom Schedule if you want to specify your preferred times.On Google Pixel phones and some other standard Android devices running Android 8.0 Oreo and later, you can find a Blue Light Filter option by going to Settings > Display > Night Light.Tap Schedule to specify your own hours and change the level of filtering with the slider called Strength.You can also tap Dusk to Dawn on to turn it on automatically at night and turn it off in the morning.Different manufacturers have coined different names for their blue light filters, but most have one.You'll usually find a quick settings option in the notification center and scheduling options in Settings > Display.LG calls it Comfort View;HTC and OnePlus, Night Mode;Huawei, EyeCare;Motorola, Night Display, and Xiaomi, Reading.If you're unlucky enough to use a phone without a blue light filter, or if you don't like the option it has, you can always try a third-party app.Our favorite blue light filter app on Android is Twilight.It allows you to set several different profiles to schedule on and off times, and can automatically detect your location to turn the blue light filter on and off at dusk and dawn.If you use a computer, be it laptop or desktop late at night, check out how to use a blue light filter on PC or Mac.Enhance your lifestyle Product review, technology news, tools to navigate the digital world.