Sorry, this gets a little complicated, but it’s the reason why a $5 bulb from Amazon may not be as good as a $60 Somnilamp (to which I have no financial connection).
Bottom line: the amber bulb doesn’t emit much blue, that’s good, but it let’s some green get through, and green is a close cousin of blue. Close enough to mess with your sleep rhythm just like blue does.Gooley So to be really sure you’re not getting any blue, you need a no-blue LED. That’s what’s in the Somnilamp.
Okay, if you want even more detail, here are the spectral graphs of each to back up that conclusion.
Here’s the amber light from Amazon. Note the green peak, that’s the problem. There’s even a little hump of blue.
Now compare the Somnilamp approach (no blue, no green — at all):
Both images are from ledmuseum (link pending). Provided to me by the Somnilamp guy. But you can’t really argue with the graphs, or the study above that shows, yes, green can mess with you.