LEDs are fast replacing other types of bulbs. In addition to being efficient and long lasting, they also provide some interesting options with lighting color, not only different colors themselves, but different shades of white.

I notice a trend now on new aircraft - they are often going with the true white LED lighting. This is good for color rendition, but... I find it kind of cold. If you have been on the newer CRJs or E175s you will notice how the white light is almost blue in tinge. This is different from the old Fluorescent lighting which was a little bit warmer, although often they mixed different color temperatures and you would get that weird magenta/yellow green tinge.

This bothers me a bit. on the other hand I also know i am particularly sensitive to light color temperature. Does anyone else notice this?

I don't like blue spectrum LED as it makes it harder to sleep. I wish they would release LEDs without the blue...

Yea, for restfulness, physiologically, you can't do much worse than blue.

When I sleep, I tend to close my eyes (and use eyeshades), so I'm not sure the color of the mood lighting makes any difference to me! I for one love some of the new lighting schemes, when awake. So much more pleasant than crappy, flickering fluorescents with sickly yellowing output.

I guess that does kind of answer my question.

I am not in fact talking about the mood lighting (the color changing led lighting, usually above the overhead bins). I am talking about the general cabin lighting.

The next time you are on a new Embraer 175, or CRJ 700 or 900, look at the overhead lights and the reading lights. on the new aircraft, these are all LEDs.

These LEDs, to me at least, have a very different feel than the old cabin lighting, which was usually a combination of fluorescent tubes and either tungsten or halogen reading lights. The new LEDs have a cool very white feel to them, verses a warmer glow from the old kind of lighting. In lighting terms, this slight color change is called color temperature, and ranges from warm (yellow) on one side to cool (blue) on the other. Even fluorescent lights have different colors - sometimes you will notice in your office or even on some planes some bulbs seem to have a more magenta tint, while others look a sickly yellow green. These are different color temperature bulbs.

I tend to notice this a lot. In some of the newer aircraft with LED lighting, they have a very "cool" color tinge to them. While this looks clean, I find it kind of cold and harsh after a while. But I guess that is something I am noticing more than other people.

Nice

So the dim/bright settings account for sleepy/active moods of the passengers but what are the colours accounting for? The mood of the crew? Blue=cannot be bothered, red=angry?

It couldn't be the passengers' mood unless you have individual settings in Biz. That would be subtle way e.g. to tell other crew members that a pax is intoxicated ...