OS X supports five different sleep modes:

  • 0 – Old style sleep mode, with RAM powered on while sleeping, safe sleep disabled, and super-fast wake.
  • 1 – Hibernation mode, with RAM contents written to disk, system totally shut down while ‚Äúsleeping,‚Äù and slower wake up, due to reading the contents of RAM off the hard drive.
  • 3 – The default mode on machines introduced since about fall 2005. RAM is powered on while sleeping, but RAM contents are also written to disk before sleeping. In the event of total power loss, the system enters hibernation mode automatically.
  • 5 – This is the same as mode 1, but it‚Äôs for those using secure virtual memory (in System Preferences -> Security).
  • 7 – This is the same as mode 3, but it‚Äôs for those using secure virtual memory.

Check which mode you’re in now.

pmset -g | grep hibernatemode

Make a note of which mode it is (probably 3) so that you can return to it if you want.

Now, set your MBP to use mode 0:

sudo pmset -a hibernatemode 0

Now, you may be wondering…if my MBP was writing memory out to disk, is that stored somewhere, taking up precious disk space? Yes! Here’s how to recover it:

sudo rm /var/vm/sleepimage

Now, a word of warning: if you change to sleep mode 0 on a MBP, you lose the ability to do a battery swap without pluggin