So I have pretty bad sleep apnea. Did the whole sleep study a few years back and now I have a CPAP. Problem solved-ish.
My CPAP can be, of course, turned on and off. It also has a few configuration features - optional alarm if my mask comes off, a “ramping” feature where the back-pressure can start lower and rise to its optimal setting, etc. - and therefore has several buttons. They are, as is the style, lit by LED.
My medical device, that is constructed to help people get better, more productive sleep, has three big, bright, BLUE LEDs.