LED lighting can "wreak havoc with the internal body clock of nocturnal animals." I am skeptical.

[MichaelEmouse]

@scr4

By the way, white LED bulbs do have a significant blue component that doesn’t exist in fluorescent and halide lamps - see here for example, see the peak at 450 nm? That’s because the actual LED emits at that wavelength, and some of that lamp is converted by a phosphor into red & yellow light, which balances out the light and makes it look white. This may be why white LEDs have a greater impact than other “white” light sources.

If you wear strong eyeglasses, you can often see this - find a small LED lamp (e.g. penlight), and turn your head so you’re looking at the LED through the edge of the eyeglasses where the lens curvature is greatest. With an incandescent bulb, the chromatic aberration of the lens turns it into a smear. But with an LED, it splits it into a blue dot and a red/yellow smear.

Does this phenomenon occur because of the difference in the index of refraction of the media? Does that same phenomenon also occur in the eye with whatever the light has to pass thru before being turned into an electrical signal? If so, does that mean we often get chromatic aberration with the naked eye, it’s just too slight in angle and intensity for us to notice it?

[scr4]

@MichaelEmouse

Does this phenomenon occur because of the difference in the index of refraction of the media?

Yes.

Does that same phenomenon also occur in the eye with whatever the light has to pass thru before being turned into an electrical signal? If so, does that mean we often get chromatic aberration with the naked eye, it’s just too slight in angle and intensity for us to notice it?

That is my understanding. On-axis (at the center of your eye’s field of view), the aberration mostly manifests as softening of the image, but it is a small effect. (Though this may be one reason why it’s hard to read writing in purely blue or purely red lighting. Though that has more to do with the green cones being more sensitive than red or blue.)

Off-axis (away from the center), the retina has much lower resolution (lower concentration of receptors), so it’s not very noticeable. Also, the brain can correct for it to some extent. Off-axis, chromatic aberration causes blue light and red light from the same source lands at different points on the retina. It’s a consistent offset so the brain just knows which blue cones and which red cones correspond to the same place.

Modern cameras actually do the same - in addition to the lens itself being designed to correct for chromatic aberration, the image processing corrects for the residual chromatic aberration by shifting the red/blue pixel signals slightly.

Disclaimer: Optics is my specialty, biology/medicine is not.

[jtur88]

@spifflog

I can believe it. There have been several studies that how that using your cell phone right before you go to be causes sleep issues. My wife and I stopped using our phones and hour before we went to be and it’s help us a lot. For millions of years with the sun went down it got dark. Not any more and that’s a rapid change from now.

.

If you’re using your cell phone to call me at that hour of the night, you’d certainly be causing sleep issues at my house. Who do you call an hour before bedtime?

[Terminus_Est]

@jtur88

If you’re using your cell phone to call me at that hour of the night, you’d certainly be causing sleep issues at my house. Who do you call an hour before bedtime?

These days, phones can do things other than call people.

[Knight_Of_Few_Words]

Blue light suppresses melatonin production, the hormone that regulates sleep. Here’s a Scientific American article on the subject (The Daily Mail is indeed clickbait swill, especially their science coverage, but even they pick up on genuine issues from time to time.)

In my personal experience avoiding bright and blue light late at night has made a huge difference to my sleep quality. It now usually takes me a few minutes to get to sleep instead of an hour or more. I use f.lux on my PC and eye comfort mode on my phone and tablet, to dim and redden their screens.