The breathing light – officially “Sleep Indicator Light” – debuted in the iconic iBook G3 in 1999.

It was originally placed in the hinge, but soon was moved to the other side for laptops, and eventually put in desktop computers too: Power Mac, the Cube, and the iMac.

The green LED was replaced by a white one, but “pulsating light indicates that the computer is sleeping” buried the nicest part of it – the animation was designed to mimic human breathing at 12 breaths per minute, and feel comforting and soothing:

Living through that era, it was interesting to see improvements to this small detail.

The iMac G5 gained a light sensor under the edge of the display in part so that the sleep indicator light wouldn’t be too bright in a dark room (and for older iMacs, the light would just get dimmer during the night based on the internal clock).

In later MacBooks, the light didn’t even have an opening. The aluminum was thinned and perforated so it felt like the sleep light was shining through the metal:

And, for a while, Apple promoted their own display connector that bundled data and power – but also bundled a bit of data, which allowed to do this:

Back when I had a Powermac G4 plugged into an Apple Cinema Display, I noticed something that was never advertised. When the Mac went to sleep, the pulsing sleep light came on, of course, but the sleep light on the display did too... in sync with the light on the Mac. I’ve tested that so many times, and it was always the same; in sync.

Just a little detail that wouldn’t sell anything, but just because.

Even years later, some people tried to recreate it on their own:

To do this I shifted the first gaussian curve to that its domain starts at 0 and remains positive. Since the time domain is 5 seconds total and the I:E ratio is known, it was trivial to pick the split point and therefore the mean. By manipulating sigma I was able to get the desired up-take and fall-off curves; by manipulating factor “c” I was able to control for peak intensity.

But at that point, in the first half of 2010s, the breathing light was gone, victim to the same forces that removed the battery indicator and the illuminated logo on the lid.

I know each person would find themselves elsewhere on the line from “the light was overkill to begin with” to “I wished to see what they would do after they introduced that invisible metal variant.”

I know where I would place myself.

This blog is all about celebrating functional and meaningful details, and there were practical reasons for the light to be there. This was in the era where laptops often died in their sleep – so knowing your computer was actually sleeping safe and sound was important – and the first appearance of the light after closing the lid meant that the hard drives were parked and the laptop could be moved safely.

The breathing itself, however, was purely a humanistic touch, and I miss that quirkiness of this little feature. If a save icon can survive, surely so could the breathing light.