Here is what is displayed in the Terminal:
Assertion status system-wide:
BackgroundTask 0
ApplePushServiceTask 0
UserIsActive 1
PreventUserIdleDisplaySleep 0
PreventSystemSleep 0
ExternalMedia 0
PreventUserIdleSystemSleep 1
NetworkClientActive 0
Listed by owning process:
pid 59(UserEventAgent): [0x00000191000b8210] 00:02:56 BackgroundTask named: "com.apple.backupd-auto"
Created for PID: 90.
pid 720(backupd): [0x000001af0001823e] 00:02:26 PreventUserIdleSystemSleep named: "Time Machine backup"
pid 720(backupd): [0x000001af000b823d] 00:02:26 BackgroundTask named: "Time Machine backup"
pid 117(hidd): [0x0000002500098046] 00:00:00 UserIsActive named: "com.apple.iohideventsystem.queue.tickle.4294968649.3"
Timeout will fire in 900 secs Action=TimeoutActionRelease
pid 274(mds_stores): [0x00000215000b8278] 00:00:44 BackgroundTask named: "com.apple.metadata.mds_stores.power"
pid 410(sharingd): [0x0000023200018282] 00:00:14 PreventUserIdleSystemSleep named: "Handoff"
Kernel Assertions: 0x10c=USB,BT-HID,MAGICWAKE
id=502 level=255 0x4=USB mod=12/31/69, 4:00 PM description=com.apple.usb.externaldevice.14300000 owner=IOUSBHostDevice
id=504 level=255 0x4=USB mod=12/31/69, 4:00 PM description=com.apple.usb.externaldevice.14600000 owner=MacBook Air SuperDrive
id=505 level=255 0x100=MAGICWAKE mod=12/31/69, 4:00 PM description=en1 owner=en1
id=506 level=255 0x8=BT-HID mod=12/31/69, 4:00 PM description=com.apple.driver.IOBluetoothHIDDriver owner=AppleHSBluetoothDevice
id=507 level=255 0x8=BT-HID mod=12/31/69, 4:00 PM description=com.apple.driver.IOBluetoothHIDDriver owner=AppleHSBluetoothDevice
Idle sleep preventers: IODisplayWrangler