If you wake up every morning groggy, it might not be your pillow or the temperature in the room that’s keeping you from getting a good night’s sleep: It could be your smartphone addiction.

A new study from Deloitte found that one third of adults check their phones if they wake up in the middle of the night, as do nearly half of those under the age of 35.

Researchers have known for years that the blue-ish light smartphone screens emit can make it harder to fall back asleep. A small subset of this late-night phone-checking group makes it even harder on themselves, though, reading and even responding to work emails during the wee hours, a behavior that’s more common among users under the age of 35.

Roughly one in 10 smartphone users will check text messages in the middle of the night, a figure that climbs to more than one in five for the under-35 age group.

Deloitte, which surveyed the habits of more than 4,000 mobile phone users in the U.K., also found that 10% of people look at their phone the instant they wake up, and a third do so within five minutes. More than a quarter of us look at our phones within five minutes of going to bed. That’s far too short a window, according to the report. “Exposure to light, including that from a screen just before going to sleep, can confuse the brain into thinking it is still daytime, and inhibit the process of falling asleep,” the study said. Experts have recommended an hour of screen-free time before bed, but Deloitte found that fewer than 25% of people actually do this.

One suggestion the study offers is to put the phone out of reach instead of right on the nightstand to resist the temptation, but for many people, that would also mean having to jump out of bed and go across the room to turn off their alarm in the morning. Another option would be to download an app that tracks your screen time—some, meant for parents who want to limit their kids’ time with electronic devices, even have a lockout function after a set time period—or rewards you for staying off your device.

Alternately, if you can’t resist late-night email-checking, you might want to consider swapping out the blue screen tint for a reddish or orange one, which scientists say is less disruptive to sleep. Apple’s iOS 9.3 has a feature called Night Shift that switches to a red-hued background; a similar app for Android users is Twilight. But really, you should just turn it off. That email from your boss will still be there in the morning.