How to Use Your Phone Before Bed

The Truth About Night Mode

If you’ve heard anything about sleep science, it’s probably that you’re not supposed to use screens before bed. And if you’re anything like me, you’ve probably ignored that advice after all, even sleep experts can’t always resist the temptation. But have you ever wondered if there’s a way to use your phone at night without completely ruining your sleep schedule? I spoke with Rohan Nagare, a sleep researcher who’s coauthored several papers on this topic, to find out.

Turns out, our sleep schedule is more flexible than we might think. But first, let’s quickly review how our body responds to natural light like sunlight and how it affects our sleep.

You’ve likely noticed that you start feeling sleepy as night falls. This happens because your body produces melatonin, a hormone crucial for sleep. Melatonin isn’t just any hormone it’s your body’s internal timekeeper. When you’re exposed to bright light from the sun in the morning, melatonin production is suppressed, making you feel awake and alert.

But it’s not just sunlight that influences melatonin production; the color temperature of light also plays a role. Daylight, which is about 5600 Kelvin, has a blue hue, while the light from a sunset, at around 3000 Kelvin, is warmer. This natural shift in color and brightness tells your body it’s time to start producing melatonin, making you feel sleepy.

Natural light makes this process simple, but things get more complicated when we introduce artificial light, especially from our phones. At their baseline, phone screens have a color temperature of 5600 Kelvin, which mimics daylight. This blue light suppresses melatonin production, which is why using your phone before bed can disrupt your sleep.

You might be thinking, “But don’t phones have a night mode to counteract this blue light?” They do. Night mode or Night Shift reduces the amount of blue light your screen emits by shifting the color temperature to a warmer hue. But does it really work?

In 2019, Rohan coauthored a study to answer this question. The study looked at two modes: a high Color Correlated Temperature (CCT) mode, where the screen’s colors were intensely shifted to the warmer end of the spectrum, and a low CCT mode, where the shift was more subtle. Both modes suppressed melatonin, and there wasn’t a significant difference between the two.

While this might suggest that Night Shift doesn’t work, the reality is more complex. As Rohan explained, the spectrum of light is just one factor; the duration, timing, and amount of light exposure also matter. If you’re using your phone for just 20-30 minutes at night, you probably don’t need to worry. But if you’re binge-watching movies or shows for hours, that’s a different story. The cumulative effect of prolonged exposure can delay your circadian rhythm and disrupt your sleep.

Rohan also mentioned that the distance from your device impacts how much light your eyes receive. The closer you are to your phone, the more intense the light is up to four times stronger than if the device were twice the distance away. So even if you’re using a warm light source, if the brightness is too high and you’re too close, it can still be detrimental to your sleep.

But there’s a hack that can help mitigate the impact of late-night screen time. The key is creating a contrast between the amount of light you get in the morning and the light you’re exposed to before bed. By getting bright sunlight around 800 lux in the morning, you can offset the circadian disruption caused by evening screen time.

At the end of the day, though, it’s not just about blue light. What you do on your phone whether it’s doom-scrolling or watching a scary movie can be just as stimulating and disruptive to your sleep as the light itself. Understanding how to have a healthier relationship with your devices is a crucial step toward improving your sleep.