If you are a generally well-rested person, Jensen lists myriad factors that could impact your sleep beyond your phone use: caffeine, exercise, the temperature of the room, the amount of light, the amount of noise, consistency of sleep schedules and bedtime routines, and using the bed for activities besides sleeping. “There’s not one thing that works for everyone”

But the people who slept less than the average showed no difference in any measures of sleep quality, regardless of whether they used a phone at bedtime or not. Of the people in the study who slept more than the roughly seven-hour average sleep time, the people who went phone-less slept better and didn’t wake up as often during the night compared to those who used their phones. One of the few phone-related differences that the study did observe actually had to do with how much sleep participants got. “Because your need for sleep is so high at that stage that you fall asleep pretty readily no matter what you do before bed.” When people are already very sleepy, it doesn’t really matter if they’re on their phones before bed, says Jensen. Part of that result is likely due to the fact that most of the participants were college students who, according to the researchers, were already sleep-deprived. “Our hypothesis was that we would see better sleep without using the phone across the full sample,” Jensen tells The Verge, “so it was a bit surprising that we didn’t find that.” The researchers were mildly surprised that even the group of people who went phone-less before bed didn’t necessarily have better sleep on average. And while blue light and phone use do likely contribute to difficulty sleeping, there are many other variables to consider within the complexities of sleep and sleep hygiene. Still, the results for the Night Shift feature fall in line with early skepticism about how much it can help sleeplessness, especially because Apple doesn’t specify which wavelengths of light are blocked. This is only one small study that will need to be replicated at a larger scale with different samplings of people before it can be generalized. “Night Shift is not superior to using your phone without Night Shift or even using no phone at all.”

“In the whole sample, there were no differences across the three groups,” said Chad Jensen, the lead researcher of the study, in a press release. “Night Shift is not superior to using your phone without Night Shift”

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