Sleep and Hibernate settings will never be 100% reliable in any operating system, including Windows 8.1.
I can report that my experience of the same Sony VAIO laptop was as follows: with Windows 8.1 it's a pleasure to use Sleep, even Remote Desktop kicks-in straightaway. Whereas with Vista, it was a lottery whether it would ever awaken without a hardware reset / reboot. My laptop's Windows 7 experience was somewhat in-between, tolerable, but lacked the slick seamless coming-to-life of Windows 8.1.
Event Viewer (Windows System Log)
When Windows 8.1 is having a problem, I am trying to train myself to begin troubleshooting by inspecting the Windows logs. At the Metro UItype 'ev' and then look in 'Settings'.
A good place to start in the Event Viewer is with 'Summary of Administrative Events'. Follow-up by looking in the System Log and filtering for 'Kernel-Power' entries. Interesting items would include 'The last sleep transition was unsuccessful', or 'The system is entering sleep'.
I am willing to bet that 70% of all Sleep and Hibernate problems are due to inappropriate settings in the Power Options (Control Panel, Hardware and Sound). For example, if you don't see a Hibernate option on the Shutdown menu, then check whether 'Allow hybrid sleep' is set to 'on'. You could investigate by pressing the Windows key +x on a laptop, or Start Search, powercfg.cpl on a desktop computer.
Does the Bios Support Sleep Mode?
If the computer has a 'Certified for Windows 8' or Windows 8.1 then there is a good chance that all the power management features will work. It's just up to you to configure Sleep or Hybrid Sleep, or else complain to the supplier / manufacturer.
To check your computer's BIOS start by interrupting the initial boot phase - the special key is usually F2 or the delete key, else try the spacebar. If all else fails, then read the boot screen! Once you have intercepted the BIOS boot, just examine carefully any options which could enable / disable Sleep. The settings are usually,
S3 - Suspend to RAM (Sleep)
S4 Suspend to Disk (Hibernate)
|See if there any updates for your BIOS. If so a later version may cure your sleep problems.|
How to Stop Your Computer from Entering Sleep Mode
1) Navigate to the 'Power Options' (Start Search powercfg.cpl)
2) Select your power plan.
3) Click: Change plan settings.
4) Crucial Links: a) Change advanced powers settings; b) Change settings that are currently unavailable.
5) Research the myriad of settings, in particular: 'Sleep'
6) Expand: 'Sleep after'. If the device you're working on is a laptop, check both the 'Plugged in' and the 'On Battery' settings.
7) Choose: 'Never' to prevent your computer going into sleep mode.
8) Remember to click 'OK'. (Or apply if you want to configure more options.)
Windows 8.1: Where's the Standby Option?
Forget Standby. Windows 8.1 replaces XP's Standby with Sleep. Do remember that you can 'Switch User' this will save the other person's open files. Not really a sleep or hibernate setting, just an idea for specific circumstances.
Premature Waking from Hibernation
All manner of software and hardware can trigger Windows 8.1 to wake up from Sleep or Hibernate. Thus the first question to ask: 'Is this insomniac behavior due to Hardware or Software?'
USB devices are common causes for computers waking prematurely. In the case of accidental mouse activation, consider laying the mouse on its back until you find a better solution.
To troubleshoot the Sleep Mode problem visit the Device Manager
1) Control Panel --> System and Security --> System --> Device Manager.
2) Right click the suspect device
4) See if it has a Power Management Tab.
5) If so, then remove the tick next to: 'Allow this device to wake up the computer.
Hardware Example: The Network adapter --> Advanced menu
Select: 'Wake up capability'. Choose 'None'.
Plan A) Blame the Task Scheduler! Start Search, Task Scheduler. (Else look in Administrative Tools, or "C:\> taskschd.msc")
i) You are bound to find suspects.
ii) 95% of them will be innocent programs that need to be scheduled.
iii) Good luck in weeding out the true culprit(s).
Plan B) Blame a virus checker.
Plan C) Blame a virus!
Try a completely different strategy, investigate recording what is happening with Performance, however, this is a black art.
Summary of Windows 8.1 Sleep Mode and Hibernate
Ever since XP, it has been a worry whether a computer will actually awaken from Hibernate or Sleep. However, with each succeeding Windows version, sleep seems more reliable, and the Windows 8.1 computers seem to magically to wake-up when you tickle them with the mouse or Enter key.
It has always been the case that power management is more important on a laptop than a desktop, consequently they have more components to configure, for example the battery, and also the lid.
Editor's Note: This article is updated to Windows 8.1 from Guy Thomas’s "Windows 8: Sleep and Hibernation Settings."