Yosemite iMac Waking from Sleep Randomly

[codeoverride]

Noticed that my iMac with Yosemite has been waking up from sleep by itself, kinda randomly. Seems to have started after I got an iPhone 6. Any ideas what's causing it? Thanks!

 

[Bobby dazzler]

Mine keeps crashing whilst sleeping...and then restarts all by itself.

I know because I have the sound turned up and I get the Ta Da startup chords...

 

[codeoverride]

My computer was restarting by itself too but that was on Mavericks. On Yosemite it just seems to wake up by itself. I think it might have something to do with my phone because I walked in the house the other day and heard it come on.