United States Patent 6658577
It is another aspect of the present invention to provide a LED blinking pattern along with varied intensity that in combination mimics the rhythm of breathing
Brian Q. Huppi et al
For such an old patent, I’m surprised I hadn’t seen the official reasoning behind Apple’s breathing sleep-indicator before now.
Weird that the rate is at the upper limit of normal adult respiration, though. Way above that of a sleeper.