Well, I've had a very annoying issue that I've been fighting. I enabled wake-on-lan on my desktop and had it start going to sleep. This was great. Saves power and I can still remote into it. I installed the wake on lan tools on a linux box so I can wake it up remotely. However, I noticed that after it would wake up, it went to sleep really quick. Within a couple of minutes. Sometimes as quick as 2 but usually around 4 or 5. After hunting around the interwebs for a while I ran across a post on microsoft answers for windows 8 where the user was having the exact same problem. Here's the URL: http://answers.microsoft.com/en-us/windows/forum/windows_8-performance/windows-8-pro-goes-to-sleep-after-60-seconds-of/b1a32492-f9cc-4db9-ad70-987af074fa08?page=5

It would appear that when Windows does a major update, this change gets reverted to its default of 2 minutes so you may want to jot down some notes or make a bookmark.
There are 2 options, 1 is easier and cleaner than the other. I prefer option 1.

  1. Enable the advanced power settings options
    1. Open regedit and drill down to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\238C9FA8-0AAD-41ED-83F4-97BE242C8F20\7bc4a2f9-d8fc-4469-b07b-33eb785aaca0.
    2. Edit the value for Attributes and change it to 2. The default value is 1.
    3. Now, goto the advanced settings for the power (Start->Settings->Power & Sleep->Additional Power Settings->Change Plan Settings->Change advanced power settings) and you will see a new option, System unattended sleep timeout. Change that to the desired time (personally they should just match the Sleep time settings). As of Windows 10.0.10586 this is now under the Sleep parent category. (Sleep->System unattended sleep timeout)
  2. Manually do it all in the registry
    1. Open regedit, drill down to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\238C9FA8-0AAD-41ED-83F4-97BE242C8F20\7bc4a2f9-d8fc-4469-b07b-33eb785aaca0\DefaultPowerSchemeValues
    2. In each of the 3 keys, update the AcSettingIndex (running on wall power) and/or DcSettingIndex (running on battery). The values are in seconds. Be sure to either convert the number of seconds to hex or choose the decimal radio box when putting in the values.