Shenanigans! Weird "power effect"

[Bobbi Flekman]

We take an iMac. Turn it on, and notice that surely but slowly outside it is getting dark. You turn on the desk lamp (a halogen in case it matters), and simply work on. At the end of the day, when your work is done, you decide to put the machine to Sleep and give it the three fingered salute (Option-Command-Eject), the machine goes snooze. Happy that you're done, you think bye bye and flicks the switch on the desk lamp. Lo, and behold! The iMac switches itself back on!!! Huh? What? Who? Even more interesting... Why?

Is the Mac susceptible to power surges? Is turning off the light producing a power surge? Is it damaging to the machine? Should I work in the dark?

 

[timswim78]

Is the Mac susceptible to power surges? Is turning off the light producing a power surge? Is it damaging to the machine? Should I work in the dark?

You are overthinking this and missing the obvious.

The iMac has an Ambient Light Sensor (ALS). Google it.

 

[Bobbi Flekman]

You are overthinking this and missing the obvious.

The iMac has an Ambient Light Sensor (ALS). Google it.

That isn't it. Unless the ALS is extremely sensitive. The same thing happens when I switch off/on the printer. I also tried putting the lamp on a different power strip (thinking the power surge might be of influence) and it happens nonetheless.