Monitors: TN vs IPS



  • I am looking into a new monitor as my current one is failing. Is there a difference between IPS and TN monitors in terms of circadian light effects? In particular it appears IPS monitors sometimes exhibit "IPS glow" or "backlight bleed". Is the light emitted in either of these conditions sufficient to cause circadian effects? (I don't currently own an IPS monitor so I have little idea of how intense these effects are. I have only read about them.)

    If it makes a difference this, is one of the IPS monitors I am considering.

    https://www.amazon.com/PG279Q-2560x1440-G-SYNC-Gaming-Monitor/dp/B017EVR2VM/

    Thanks,

    James Fadden



  • No, it's not possible for any difference to be experienced to your circadian rhythm between IPS and TN. Consider how bright the moon is, and yet it's not bright enough to be a problem for our circadian rhythms.

    This glow is simply a minor nuisance for people who are very fussy about such things because it can be a little bit distracting when most of the picture is very dark, such as dark scenes in movies or dark parts of a video game.

    In order for your circadian rhythm to be affected, the light source has to be fairly bright and 'alerting'. A tiny amount of glow around the corners is significantly less light than the moon. So the only reason why you'd want to avoid an IPS panel is just if you think the glow would be distracting.



  • Thanks. I think the online complaints had given me an exaggerated impression of how bright these phenomena are. And photos taken in a dark room also tend to exaggerate the brightness. If they produce moonlight light levels (0.3 lux or less), I would agree I have nothing to worry about.



  • @JamesFadden said in Monitors: TN vs IPS:

    Thanks. I think the online complaints had given me an exaggerated impression of how bright these phenomena are. And photos taken in a dark room also tend to exaggerate the brightness. If they produce moonlight light levels (0.3 lux or less), I would agree I have nothing to worry about.

    I didn't say it would be as bright as moonlight. I said it would be a teeny tiny microscopic fraction of it.

    At night in your home when you have f.lux set to whatever color temperature you set it to, do you still have lights and light sources in your home that can interrupt melatonin production?


  • f.lux team

    Most monitors will achieve 500:1 luminance ratio from white to black even with backlight bleed - even though a digital camera will make it look bad, most of these effects are <1 cd/m2. Yes, they can be noticed when watching a dark movie, but for most content you will not notice.

    You should be more worried about a "small" white patch (less than 1% of the screen) than the screen glow.

    The important thing about any monitor this size is how easy they are to dim at night (or not). Compare with the 27" Apple monitor here, which uses a similar panel: https://fluxometer.com/rainbow/#!id=Thunderbolt 27/6500K-Thunderbolt27


  • f.lux team

    @TwoCables if this is the @JamesFadden I know, he has a pretty excellent handle on things that interrupt melatonin production and beyond. Hi @JamesFadden!



  • Lorna: Yes, it's me. Hi!

    Michael: Yes, if I saw a white patch, I'd be concerned (and it would certainly stand out in my usual late night condition of 1200k f.lux and ambient light of <10 lux monochromatic red.)

    Following your suggestion I checked into the dimming ability of the monitors I am considering. For the one I linked to, at 100% OSD brightness the luminance is 331cd/m^2, black point 0.29 cd/m^2. At 0% it is 55.9 cd/m^2 and 0.05 cd/m^2. My impression is that is a decent range(?) The OSD menu is adequate, but I don't usually need to use that with f.lux.


  • f.lux team

    To figure out lux at the eye from luminance you can multiply by roughly 0.4-0.5 for a 27" screen.

    1200k does allow some melanopic light, so at full brightness, you'd be seeing around 5 melanopic lux, and the lux from the "unfiltered" glow would be <0.2 melanopic lux.


  • f.lux team

    Oh and also (for @TwoCables), circadian timing / sleep and how both are affected by a full moon is an ongoing area of research. https://www.scientificamerican.com/article/it-must-be-the-moon-tired/ and https://www.theguardian.com/science/2013/jul/26/moon-influence-sleep-study are a couple good ones. There's quite a bit of debate there. Pretty cool.



  • @lorna , yes, there is a body of research on possible effects of moonlight.

    I read the most influential paper, by Cajochen et al., when it came out.

    https://www.cell.com/current-biology/fulltext/S0960-9822(13)00754-9

    There is also a good counter-argument that such findings are due to publication bias (the "file drawer problem").

    https://www.cell.com/current-biology/fulltext/S0960-9822(14)00542-9

    To which Cajochen et al. published a counter-counter-argument.

    https://www.cell.com/current-biology/fulltext/S0960-9822(14)00931-2

    More recently, in paper out just this month, Thomas Wehr published a study on the cycles of bipolar patients and found a correlation not with moonlight but with the moon's gravimetric tidal cycle. He advances "a hypothesis that the putative biological system that responds to lunar cycles has two separate, but mutually reinforcing entrainment mechanisms: one that responds to the moon’s luminance cycles and one that responds to the moon’s gravimetric tidal cycles."

    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5524624/

    I have to say it's hard to think of a plausible mechanism, at least in terms of a direct effect of the moon's gravity on the human body, since the strength of such effects is so minuscule.

    The bipolar patients in the latest paper were first studied decades ago when Dr Wehr was at NIH. Perhaps Dr. Wehr hesitated to publish such a bold hypothesis.

    (For those who may not know, Dr. Wehr was a co-author of the first paper to show light suppression of human melatonin (1979) and also made many other advances such as the first papers on S.A.D. and its treatment with phototherapy and treatment of bipolar disorder by dark therapy. He was also one of the authors of the paper on my Non-24 case.)


  • f.lux team

    @JamesFadden Thank you for this wonderful overview of the research. It's one of my favorite slow moving debates. I hadn't seen the Wehr paper yet!


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