Not me, but my venerable Mac Pro 1,1.
At some point the damn thing stopped sleeping. I’d spend time stopping apps, checking after a clean boot, looking through the output of netstat -an, etc. Nothing. Gave up and just did a lot more shutting down the machine completely. It bugged me but in a way it was good to turn it all off (less checking mail in the middle of the night…)
Today it bugged me again. On the way out to walk around the park i’d tried to sleep the beast, as usual it refused. In a fit of pique i yanked the network connection. Paranoia inspired testing? And, the machine went straight to sleep. Uh huh.
More fiddling around with Privoxy (always a candidate for being the problem in my mind), puzzling through netstat output, closing down apps., etc. More nothing. Bah.
$ pmset -g assertions 6/12/13 11:27:34 AM GMT+ Assertion status system-wide: PreventUserIdleDisplaySleep 0 CPUBoundAssertion 0 DisableInflow 0 ChargeInhibit 0 PreventSystemSleep 1 PreventUserIdleSystemSleep 0 ExternalMedia 0 DisableLowPowerBatteryWarnings 0 EnableIdleSleep 1 NoRealPowerSources_debug 0 UserIsActive 0 ApplePushServiceTask 0 Listed by owning process: pid 94: [0x0000005e012c0010] PreventSystemSleep named: "com.apple.InternetSharing"
All this time i’ve had internet sharing turned on… and had no idea that it stopped machines sleeping. Seeing as i don’t actually share internet from this machine it’s a little puzzling. No doubt it was turned on for a reason in the past, all that is lost in the mists of time.
Anyway, pmset -g assertions is the way to debug sleep issues! May Gub (or the ghost of Steve) help you if you ever need to read the manpage. At least i can now sleep my machine again!