Is blue light actually bad for sleep?

My husband and I have very different approaches to sleep. He aims to optimize: sleep masks, special cooling mattress covers, sleep-tracking watches, etc. I generally drag myself upstairs and pass out within minutes, considering the night a success if I managed to change into pajamas.

There is, however, one area where we align when it comes to sleep: no phones in bed. For years, we’ve adopted a strategy of charging our phones out of reach—either on the other side of the bedroom, or in another room altogether. This strategy is certainly supported by popular health and wellness advice, which extols the virtues of a screen-free sleep environment and warns against the grave dangers of toxic blue light emanating from our devices.

But what does the evidence actually say? How worried should we be about screens interfering with our sleep?

Party like it’s 2010 (…but then go straight to bed)

Let’s take a quick trip back to the year 2010. Obama was in the White House, the iPad and Instagram had just been released, Katy Perry’s “Teenage Dream” was playing, etc. Researchers proposed a new model for how we should understand the effect of technology on sleep.

In this model, they proposed a few potential reasons why technology use might disrupt sleep, one of which was screens’ emission of blue light. This was a potential reason because evidence was limited at the time, but the health and wellness world took it and really ran with it.

Fast forward to 2024. No more Obama, definitely still iPad and Instagram, questionable on Katy Perry.2 One of the researchers from that original paper linked up with other sleep experts, and they decided to revise the model based on all the research on technology use and sleep that’s come out in the past 14 years.

The result is this recently published review paper, which pulls together insights from all that prior research, and the results certainly challenge some of our conventional wisdom. (My favorite kind of research!)3

So, let’s (sleep)walk through it.

What did the researchers find?

The researchers offer four potential reasons why using screens in the evening could negatively impact sleep:

1. Blue light. Bright light (including concentrations of short-wavelength light, or blue light, emitted by screens) has been shown to suppress the release of melatonin. This could delay the onset of sleep.
2. Arousal. Screens may be cognitively and emotionally stimulating, which would make it harder to fall asleep.
3. Sleep disruption. Notifications and sounds from devices interrupt sleep during the night.
4. Sleep displacement. Using devices (especially in bed) delays the time when people start trying to fall asleep.4

So, reviewing the past 14 years of evidence on each of these potential reasons, what do they find?

Importantly, sleep disruption and displacement seem to be bigger drivers of sleep problems than previously assumed. For example, compared to adolescents who turn off their phones at night, those that leave the ringer on have more trouble falling and staying asleep. This is a problem, given that as many as 70% of youth reporting sending at least one text message between 10 p.m. and 6 a.m. over the course of a week. Further, use of devices at night (e.g., scrolling while laying in bed) has been shown to delay going to sleep by as much as 1 hour and 15 minutes or more.

And what about blue light?

There is evidence that blue light (and bright light in general) does suppress melatonin release, but less evidence that this actually translates to significantly less sleep. In fact, across studies, blue light seemed to delay sleep onset by only 9.9 minutes at most.

Similarly, the idea that “arousal” plays a role depends on the technology in question. Some technology use, for some people, may actually be calming. Other use—highly suspenseful or scary shows, for example—could delay sleep onset but, again, by at most only 8.5 minutes. In short: these explanations (blue light and arousal) have less evidence for them than we thought.

Finally, the researchers find evidence for “bidirectional” effects. It’s not just that technology use impacts sleep, but also that people who are already struggling with their sleep may turn to technology to try to fall asleep. No surprise to anyone who’s ever scrolled Instagram to pass the (sleepless) time, or turned on a calming Netflix show to try to manage pre-sleep stress.

What should I do with this information?

In my opinion, there are a few takeaways from the study:

1. Find what works for you

As is often the case in psychology research, we’ve failed to adequately appreciate that people are different when it comes to technology use and sleep. For some, screens before bed are a definite no-no, but for others, a relaxing TV show before bed may be just the thing to help them get to sleep. Hard-and-fast “no screens before bed” rules may not work for everyone. That said, there are good reasons to stay off screens in the time before bed (see #3), so this is something to consider carefully, especially if you’re struggling with your sleep.

2. Blue light might be overrated

There’s certainly more research to be done here, but slapping on a pair of blue light glasses seems unlikely to have a major impact on our sleep quality. Other factors may matter more.

3. Be careful of phone interruptions and sleep delays

Unsurprisingly, there is evidence that when we’re on our phones before bed, it delays the time when we actually end up going to sleep. Also, when our phones are next to us and turned on, it wakes us up. If you (like me) are prone to late-night scrolling, it makes sense to keep your phone out of reach of bed. If nothing else, make sure to put your phone on “sleep mode” or turn off notifications before going to sleep.