Worth noting that the article itself doesn't seem to cover the blue light / sleep question except to link to this 2021 paper, which is fortunately in English!
Duraccio, K. M., Zaugg, K. K., Blackburn, R. C., & Jensen, C. D. (2021). Does iPhone night shift mitigate negative effects of smartphone use on sleep outcomes in emerging adults? Sleep Health, 7(4), 478–484.
Quotes from the paper:
> There were no significant differences in sleep outcomes across the three experimental groups. Post-hoc exploratory stratified analyses revealed a significant main effect of phone condition on sleep efficiency (P = .014) and WASO (P = .013) for participants averaging more than 6.8 hours of sleep per night, with the no phone condition demonstrating the best sleep outcomes.
In other words, if you want to sleep better, don't use your phone at night. My assumption is that any improvement in sleep due to a filter would be the result of dimming the screen, since changing the native color temperature of the screen limits its maximum light output and creates a dimming effect unless the brightness is increased to compensate.
> However, there is little evidence to support the use of short-wavelength light blocking devices, such as filtering glasses or the Night Shift function, to improve sleep quality in healthy populations, although there may be a small benefit for people with insomnia.
That is interesting. Not sure how crucial this studys circumstances are for looking at this, but personally I could swear that my phone screen without a blue light filter keeps me more awake. Maybe that's just a fallacy because it definitely feels way more pleasant for me.
I recognise the same thing, but not limited to phone screens. I associate the warm dim light of incandescent bulbs with evening and winding down. I also associate bright blue light with activity and being awake.
It’s anecdotal, of course. But whenever I’m winding down and I see a bright light I can just feel my body wake up a little.
I wonder if that’s actually as physical as it feels or if it’s caused by the associations.
> such as filtering glasses or the Night Shift function
Those two are very different. Some filtering glasses can remove the entirely of the blue spectrum, while the night shift function only reduces (but not eliminates) it.
Maybe so, but you'd still expect anything capable of removing a good bit of the blue light to still show a significant improvement in sleep quality, even if the effect was not as large as with "complete" blue light removal.
I suspect that the darkening effect of changing a screen's color temperature along with the placebo effect can explain a good bit of this. Most people are not very good at assessing something as vague as "sleep quality". Robust studies are very much needed.
https://doi.org/10.1016/j.sleh.2021.03.005
Duraccio, K. M., Zaugg, K. K., Blackburn, R. C., & Jensen, C. D. (2021). Does iPhone night shift mitigate negative effects of smartphone use on sleep outcomes in emerging adults? Sleep Health, 7(4), 478–484.
Quotes from the paper:
> There were no significant differences in sleep outcomes across the three experimental groups. Post-hoc exploratory stratified analyses revealed a significant main effect of phone condition on sleep efficiency (P = .014) and WASO (P = .013) for participants averaging more than 6.8 hours of sleep per night, with the no phone condition demonstrating the best sleep outcomes.
In other words, if you want to sleep better, don't use your phone at night. My assumption is that any improvement in sleep due to a filter would be the result of dimming the screen, since changing the native color temperature of the screen limits its maximum light output and creates a dimming effect unless the brightness is increased to compensate.
> However, there is little evidence to support the use of short-wavelength light blocking devices, such as filtering glasses or the Night Shift function, to improve sleep quality in healthy populations, although there may be a small benefit for people with insomnia.