Why does my iMac wake from sleep when I turn on or off my desk light

Discussion in 'Mac Basics and Help' started by GilesM, Mar 11, 2009.

  1. GilesM macrumors 6502

    Joined:
    Oct 17, 2008
    #1
    I have a small problem, but wondering if you can help.
    If my iMac is in sleep mode and then I turn my desk lamp on or off the iMac wakes from sleep.
    At first I thought it may be to do with the iMac and the light being on the same power supply, and the turning on or off of the light causing a dip or spike in voltage being detected by the iMac. Is this possible?

    However yesterday my iMac woke from sleep when i turned off the main light in the room off, which is of course on a different ring circuit.

    Any ideas? Is this a potential danger for my iMac?
     
  2. Sambo110 macrumors 68000

    Joined:
    Mar 12, 2007
    Location:
    Australia
    #2
    Sometimes ours goes off sleep when I am playing the PS3 in a different room. No idea what causes it though, maybe the mouse moves slightly?
     
  3. thomahawk macrumors 6502a

    thomahawk

    Joined:
    Sep 3, 2008
    Location:
    Osaka, Japan
    #3
    somestimes i think the isight thing watches for light changes or whatever. i sometimes turn on my light in my room and my macbook turns on or off. or when i walk past it and it turns on or off (directly in front of the camera range of course) and theres no external mouse connected to it. just the trackpad and good old keyboard
     
  4. Cabbit macrumors 68020

    Cabbit

    Joined:
    Jan 30, 2006
    Location:
    Scotland
    #4
    And easier one is your vibrations move the mouse which triggers the wake from sleep.
     
  5. BlueRevolution macrumors 603

    BlueRevolution

    Joined:
    Jul 26, 2004
    Location:
    Montreal, QC
    #5
    The camera is only active when the green light is on, and certainly not during sleep.
     
  6. GilesM thread starter macrumors 6502

    Joined:
    Oct 17, 2008
    #6
    I will try some experiments to see if it is the power issue or the vibration issue, i.e. remove the light from the power, put the iMac to sleep and then flick the switch and see if the iMac wakes, if it does then it is vibration, not power.
    Thanks for the idea.
     
  7. OneBlueFire macrumors member

    OneBlueFire

    Joined:
    Oct 12, 2008
    Location:
    Manila, Philippines
    #7
    ALS (Ambient Light Sensor)

    Go to System Preferences -> Displays
    Uncheck "Automatically adjust brightness as ambient light changes"
     
  8. GilesM thread starter macrumors 6502

    Joined:
    Oct 17, 2008
    #8
    Really, "Ambient Light Sensor" how cool is that!:)
    I will give it a try, thank you!
     
  9. mikalm macrumors newbie

    Joined:
    Jul 7, 2008
    #9
    Mac wakes up from sleep when room light goes off

    I had the same problem, and finally figured it out. It was my battery power backup system connected to my Mac via USB that would alert the Mac, (waking it up) to any minute power variation it detected. I disconnected the USB cable from the backup battery, and problem solved! The Mac now stays asleep until I wake it up.:)
     
  10. spinnerlys Guest

    spinnerlys

    Joined:
    Sep 7, 2008
    Location:
    forlod bygningen
    #10
    I had that too, it has to do with the power surge that goes on by switching a device on or off which is on the same circuit.

    It has nothing to do with vibrations, as only a click or pressing of a key is registered by the Mac OS. Moving your mouse doesn't trigger waking from sleep.
     
  11. BlueRevolution macrumors 603

    BlueRevolution

    Joined:
    Jul 26, 2004
    Location:
    Montreal, QC
    #11
    It does for me, as does unplugging my iPod.
     
  12. spinnerlys Guest

    spinnerlys

    Joined:
    Sep 7, 2008
    Location:
    forlod bygningen
    #12
    That's strange, the moving part at least. If it is an optical mouse with a red/blue/coloured light, is it turned on while your Mac is fast asleep?

    The unplugging your iPod I understand, as removing any kind of USB device (the cable) seems to wake a Mac.

    But sometimes it doesn't, hmmm.
     
  13. BlueRevolution macrumors 603

    BlueRevolution

    Joined:
    Jul 26, 2004
    Location:
    Montreal, QC
    #13
    I have a Logitech cordless mouse, so it is still powered when the computer is asleep.
     

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