Zero tolerance blue light?

March 6, 2019 6:49 PM

I'm trying to improve my sleep hygiene by reducing blue light exposure. But how does that actually work? How much blue light is too much? Does a glance here and there ruin my efforts for the evening? Can I have it in my peripheral vision?

I'm looking for more of the science behind this than anecdotal evidence, but your experiences are still welcome. When they say "no screens for an hour before bed," how strict is that? If I glance at my phone for a few seconds here and there in that hour, is it just going to make my sleep slightly worse, or does it completely "reset" any of the effects of not looking at my phone?

I ask for two reasons:

1) I have routines/habits that I occasionally finish up in that hour before bed and need to check them off so I know the next day that I did them and don't need to catch up on them. I also sometimes glance at my phone for the time. I could buy an analog clock for my bed side, and have a paper checklist, but do I need to do that?

2) My partner is blessed with the ability to be asleep within 10-15 minutes despite spending an hour every night on their phone in bed. Their screen is in my peripheral vision, and sometimes I'll glance at it. They also like to occasionally show me things on it (they try to refrain, knowing I'm "trying to save my eyes" as they call it, but they have impulsivity issues and sometimes just really have to show me the cute dragon they just hatched). Even if they don't show me things, will having it in my peripheral vision contribute to keeping me awake?

So the two main questions are: if I glance at my phone after not looking at it for half an hour, have I just ruined all the benefits of not looking at my phone? And if I don't look directly at the phone, but someone else is using it in my peripheral vision, is that going to keep me awake too?

I apologize if this is not very coherent. I am tired and just want some good sleep.

posted by brook horse to Health & Fitness (3 answers total)

I think that the idea is to avoid all blue light before sleep, including short glances, though I can't point you to a study. I just wanted to mention that if you really need to check your phone, you could consider getting blue-light-blocking glasses to keep next to your bed.
posted by pinochiette at 7:27 PM on March 6, 2019 [1 favorite]

Best answer: Most of the studies I've seen seem to test the 2-hour mark for light exposure before measuring sleep effects; brief exposure to blue light would be so variable and dependent upon the person that it would be harder to test. I don't think glances would completely "reset" the effects of avoiding your phone, but it is true that the longer you're exposed to blue light then the worse your sleep will be.

According to a self-reported study,

Sending/receiving text messages and/or phone calls after lights out significantly predicted respondents' scores on the PSQI, particularly longer sleep latency, worse sleep efficiency, more sleep disturbance and more daytime dysfunction. ... An increase in bedtime mobile phone use was associated with more fatigue and later rise times among younger respondents (≤ 41.5 years old and ≤ 40.8 years old respectively); but it was related to an earlier rise time and shorter sleep duration among older respondents (≥ 60.15 years old and ≥ 66.4 years old respectively).

My question/suggestions:
If you're an iPhone user, do you use Night Shift? If not, can you get f.lux or Twilight installed on your phone? I've seen reports that iPhone's Night Shift is about equal to f.lux's incandescent setting (2700K), which is okay-but-not-great -- if you can dim your screen, it seems to help more.

Also, get your partner on board for this as well, especially since they keep wanting to show you things when you're trying to avoid light. It will only help their sleep, regardless of how quick they can fall asleep compared to you.

tl;dr, dim your screen when you need to look at it, use Night Shift/f.lux/etc., keep on avoiding blue light
posted by lesser weasel at 11:01 PM on March 6, 2019 [1 favorite]

The way the system works, as far as I can tell, is that your liver is constantly removing the melatonin (sleep hormone) from your body. It will remove half the melatonin in 30-50 minutes. So your pineal gland needs to keep producing melatonin to keep you asleep / sleepy. It will only do this if you are not getting exposed to blue light at a specific frequency. (Even if you are blind!) So my non-medical guess is that short exposure to light will only have a proportionally small effect on your melatonin levels. Daylight is super, super bright compared to interior light, so incidental exposure is just that. I do like Night Shift et al., though because of the way LCD screens work I'm not convinced they work like the blue-blocking glasses. It is, unquestionably, an excellent cue that you should be going to bed soon.
posted by wnissen at 9:36 AM on March 7, 2019