Wednesday, May 5, 2021 [Tweets] [Favorites]

Night Shift Sleep Study

Tim Hardwick:

Now found on most smartphones in some form, Night Shift is based on studies that have demonstrated that blue light can negatively impact sleep by altering the body’s circadian rhythm. However, the results of a new study from BYU published in Sleep Health have undermined that premise.

To test the theory, BYU psychology professor Chad Jensen and researchers from the Cincinnati Children’s Hospital Medical Center compared the sleep outcomes of individuals in three categories: those who used their phone at night with the Night Shift function turned on, those who used their phone at night without Night Shift, and those who did not use a smartphone before bed at all.

John Gruber:

My theory all along has been that Night Shift just makes your screen look hideously mis-colored.

Sleep benefits or not, I do find it more comfortable. Perhaps BYU’s results differ from previous studies because Night Shift shifts the colors much less than f.lux or blue light glasses.

Previously:

Update (2021-05-06): f.lux:

The first thing to show is any difference between using a phone and not using one - this study doesn’t show any difference, with P>0.5. So that’s the headline really.

We don’t know if this is just underpowered, or if dimming + night modes are “enough” for most people.

Even so, Night Shift is not doing very much - f.lux is about 7x stronger by default.

To sum up: If you can’t even show you have a problem, you cannot fix it, and making a very minor change probably won’t fix it anyway.

I like Night Shift because I run my devices in Light Mode. But I bet it offers much less blue light benefit for those running in Dark Mode all the time, or in Automatic mode where the phone automatically switches to Dark Mode at night. With so much less white content in Dark Mode, the effect of Night Shift is much more subtle. If most users are using Dark Mode at night, anyway, that could also explain why the study found no significant difference vs. not using a phone at all.

John Gruber:

I’ve long heard from friends and readers who enjoy Night Shift (and f.lux) simply because they feel it reduces eye strain. Comfort is comfort — if you Night Shift feels easier on your eyes, go ahead and use it. What I object to is the “may help you get a better night’s sleep” claim. Apple should keep the feature but change the language describing it to remove any suggestion that it’s a sleep aid, unless subsequent studies suggest otherwise.

4 Comments

Night Shift Man

> Sleep benefits or not, I do find it more comfortable

Agreed.
I wonder why there are always people meaninglessly against something.

The "theory" is completely pointless without demystifying why people feel beeter with the feature.

Philip Dhingra

This is one of those subjects that is difficult to study both anecdotally and academically.

I don't have access to the original BYU study's PDF, but I bet they didn't control for indoor lighting conditions. So, unless you turn off every other light in your house, Night Shift is going to be a drop-in-the-bucket.

My suggestion:

Turn off all your lights at 11 PM and keep your blinds shut until 7 AM. This will get you 50% of the way there. Furthermore, turn on Night Shift and manually reduce the brightness of all your screens at night; that'll get you 35% of the remaining 50%.

While I can't do a randomized controlled trial to prove it, this routine has impacted me some. Whenever 11 rolls around, I feel the tug of sleep more strongly than if I wasn't following any rules.

I came up with this program after reading Richard Korezkwa's "Why indoor lighting is hard to get right and how to fix it." Even though the article isn't strictly academic, it also isn't bro-science. It's somewhere in the middle, which is the best we can do.

https://www.lesswrong.com/posts/7izSBpNJSEXSAbaFh/why-indoor-lighting-is-hard-to-get-right-and-how-to-fix-it

"I wonder why there are always people meaninglessly against something."

Because some people would rather know what's true, instead of trusting their feelings. I think that's generally a good approach to most things in life. I don't find it meaningless at all, quite the opposite.

A priori, it's just not very plausible that these filters would work. Our eyes are calibrated to the sun, and the sun is incredibly bright. It just doesn't seem likely that screens, which are neither very big, nor very bright, would have a huge impact on our sleep patterns. The research seems to support that: if there is an effect, it's elusive, and thus not very large.

Having said that, if a red screen makes you happy, then make your screen red. If the red screen becomes part of your "going to sleep now" ritual, that's helpful regardless of any actual physical effects.

>A priori, it's just not very plausible that these filters would work. Our eyes are calibrated to the sun, and the sun is incredibly bright. It just doesn't seem likely that screens, which are neither very big, nor very bright, would have a huge impact on our sleep patterns.

I think the (pseudoscientific) idea is that our brains are expected to see something as bright as the sun during daytime, not at night, and that they get confused (and alert and awake) when that brightness continues late at night.

(Personally, I vaguely recall finding f.lux too strong even at its weakest setting, but have been using Night Shift. It's fine. Perhaps the best thing I can say is that I don't really notice it at all most days, except when it suddenly turns off, such as because of rebooting.)

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