(display sleep prevented by ) <

I've been having trouble getting my mac's display to sleep. It happens on my normal user account, and also, on a dummy user account too. It's quite annoying because it then ghosts my monitor by morning with some very "deep grooves"

to mitigate this, i've set my screensaver to run, for the first time since i got off CRTs.

Anyone have any ideas??? Doesn't it look like my system should sleep, at least the display? I don't want a full sleep.

Anyway, I'm a pretty clever user, so I looked around. This is interesting:

Doing a:

pmset -g

in terminal gets me this:

Currently in use:

hibernatemode 0

halfdim 1

womp 0

networkoversleep 0

sleep 0

powerbutton 1

ttyskeepawake 1

hibernatefile /var/vm/sleepimage

autorestart 0

disksleep 10

displaysleep 3 (display sleep prevented by )

By blank.... yes there is a space there with nothing in it. I verified that the output doesn't always have this by looking on my wife's "my" laptop, and indeed this isn't normal for 10.8.5 --- oh sorry, that is the system i'm on.

I saw another post about this in another thread, but it was answered that the user should unplug all devices. However, I have changed nothing, and to my knowledge, it's all working properly. It's just two hard drives anyway, and they seem to be sleeping fine, as they spin up with an ask from the system.

pmset -g assertions

9/20/13 3:38:40 AM EDT

Assertion status system-wide:

PreventUserIdleDisplaySleep 0

PreventSystemSleep 0

PreventUserIdleSystemSleep 0

ExternalMedia 1

DisableLowPowerBatteryWarnings 0

UserIsActive 0

ApplePushServiceTask 0

BackgroundTask 1

Listed by owning process:

pid 28(powerd): [0x000000090000012c] 12:40:02 ExternalMedia named: "com.apple.powermanagement.externalmediamounted"

pid 28(powerd): [0x0000000d00001277] 00:00:53 InternalPreventDisplaySleep named: "com.apple.powermanagement.delayDisplayOff"

Timeout will fire in 7 secs Action=TimeoutActionRelease

pid 28(powerd): [0x0000000d0000127d] 00:00:39 InternalPreventDisplaySleep named: "com.apple.powermanagement.delayDisplayOff"

Timeout will fire in 21 secs Action=TimeoutActionRelease

pid 28(powerd): [0x0000000d0000127f] 00:00:22 InternalPreventDisplaySleep named: "com.apple.powermanagement.delayDisplayOff"

Timeout will fire in 37 secs Action=TimeoutActionRelease

pid 28(powerd): [0x0000000d00001281] 00:00:04 InternalPreventDisplaySleep named: "com.apple.powermanagement.delayDisplayOff"

Timeout will fire in 55 secs Action=TimeoutActionRelease

pid 4817(helpd): [0x0000000c000010cb] 00:43:52 BackgroundTask named: "com.apple.helpd.sdmbuilding"

Kernel Assertions: 0x0140

* Kernel Assertion ID = 500

Created At = 12/31/69 7:03:06 PM EST

Modified At = 9/19/13 2:59:53 PM EDT

Owner ID = 0xffffff80a5283000

Level = 255

Assertions Set = None (4)

* Kernel Assertion ID = 501

Created At = 12/31/69 7:03:10 PM EST

Modified At = 9/19/13 10:23:43 PM EDT

Owner ID = 0xffffff80a5290000

Level = 0

Assertions Set = None (4)

* Kernel Assertion ID = 502

Created At = 12/31/69 7:04:54 PM EST

Modified At = 12/31/69 7:00:00 PM EST

Owner ID = 0xffffff80a5246000

Level = 0

Assertions Set = None (4)

* Kernel Assertion ID = 503

Created At = 12/31/69 7:04:57 PM EST

Modified At = 12/31/69 7:00:00 PM EST

Owner ID = 0xffffff80a5249000

Level = 0

Assertions Set = None (4)

* Kernel Assertion ID = 504

Created At = 12/31/69 7:05:05 PM EST

Modified At = 12/31/69 7:00:00 PM EST

Owner ID = 0xffffff80a524c000

Level = 0

Assertions Set = None (4)

* Kernel Assertion ID = 505

Created At = 12/31/69 7:05:08 PM EST

Modified At = 12/31/69 7:00:00 PM EST

Owner ID = 0xffffff80a524f000

Level = 0

Assertions Set = None (4)

* Kernel Assertion ID = 506

Created At = 12/31/69 7:05:11 PM EST

Modified At = 12/31/69 7:00:00 PM EST

Owner ID = 0xffffff80a528d000

Level = 0

Assertions Set = None (4)

* Kernel Assertion ID = 507

Created At = 9/19/13 3:12:43 PM EDT

Modified At = 9/20/13 2:40:43 AM EDT

Owner ID = 0xffffff8015b75c00

Level = 0

Assertions Set = None (256)

* Kernel Assertion ID = 508

Created At = 9/19/13 3:11:43 PM EDT

Modified At = 12/31/69 7:00:00 PM EST

Owner ID = 0xffffff8017c70c00

Level = 255

Assertions Set = None (8)

* Kernel Assertion ID = 566

Created At = 9/20/13 3:52:59 AM EDT

Modified At = 12/31/69 7:00:00 PM EST

Owner ID = 0xffffff8015abe100

Level = 255

Assertions Set = None (128)