Switching on light causes iMac to wake from sleep

Sad Professor

I know this might sound crazy. But I've noticed this recently, although it doesn't always happen so its difficult to test. At first I thought I was hitting the mouse accidentally but no, switching on my desk light actually does sometimes cause my iMac to wake from sleep. They are both plugged into the same 6-way extension lead so my first (scary) thought was that it might be a electrical surge or spike. But the lead is also a surge protector so this seems strange. Could the iMac's IR sensor be affected by the light?

Has anyone ever heard of this happening? Any ideas?

merritt

Is there a chance that turning the desk light on causes a little vibration on the desk? If you have a mouse connected, that might be enough to wake your Mac.

formatman

USB seems to affect it alot

Eg m if the mac is asleep switching off a connected printer will often wake it up

So a power surge is proably effecting a USb device which in turn is waking the mac

gerry87

whenever i turn on my desk light my PC speakers crackle and the screen flickers... the screen also flickers when someone turns on a shower . I won't even attempt to explain, i have no idea.

Sad Professor

merritt wrote:

Is there a chance that turning the desk light on causes a little vibration on the desk? If you have a mouse connected, that might be enough to wake your Mac.

This is what I thought as first but I'm pretty certain now that this is not the case.

formatman wrote:

USB seems to affect it alot

Eg m if the mac is asleep switching off a connected printer will often wake it up

So a power surge is proably effecting a USb device which in turn is waking the mac

Interesting. I do have an external hd so perhaps that may be the cause.

It seems like it's probably an electrical surge of some kind so I'll probably just be safe and plug the light in somewhere else. It's still worrisome to think it could effect the imac even with a surge protector.

tywy

gerry87 wrote:

whenever i turn on my desk light my PC speakers crackle and the screen flickers... the screen also flickers when someone turns on a shower . I won't even attempt to explain, i have no idea.

Yeah that happens in my house too...an electric shower requires a good deal of power so the rest of the stuff on the circuit is stepped down so that the shower can be given the adequate amount of power. My light just dims slightly, nothing happens to my macbook though.

OP, I think it's probably your mouse if it's an anywhere near decent optical mouse. If I tap my desk when my mouse is plugged in and the screensaver is on the screensaver will turn off. I don't think it's anything to be worried about anyway.

tywy

also correct me if I'm wrong but shouldn't your USB be protected from a power surge so that whatever is connected to it doesn't get melted?

Sad Professor

tywy wrote:

also correct me if I'm wrong but shouldn't your USB be protected from a power surge so that whatever is connected to it doesn't get melted?

You mean via the surge protector? Yes, the more expensive ones have this but the one I have is pretty cheap. I would have gotten the better/costlier USB Belkin protectors but I couldn't find one with a cable longer than 2m.

Anyway it hasn't happened since but I'm gonna switch the light to another socket when I get a chance and probably get a better surge protector in the new year.