In July 2002, Appled filed a patent for a “Breathing Status LED Indicator” (No. US 6,658,577 B2). They described it as a “blinking effect of the sleep-mode indicator in accordance with the present invention mimics the rhythm of breathing which is psychologically appealing.”

The average respiratory rate for adults is 12-20 breaths per minute, which is the rate that the sleep-indicator light fades in and out on most Apple laptops. Older models such as the Macintosh PowerBook, however, use a blinking LED indicator, with discrete pulses in one-second intervals.

The other day, I noticed that my friend’s Dell laptop had a similar feature but with a shorter fade-in-fade-out period. Its rate was around 40 blinks per second, or the average respiratory rate for adults during strenuous exercise—not very indicative of something in sleep-mode.

It’s interesting how a lot of companies try to copy Apple but never seem to get it right. This is yet another example of Apple’s obsessive attention to detail.