Newer laptop Mac’s by default use ‘Safe Sleep’. This means that when you put your Mac to sleep, it writes the contents of RAM out to the hibernation file before going to sleep. This means that if it completely runs out of power (or you remove the battery to swap it) you wont lose your work, because it will automatically have gone into hibernation.

However, this takes time, particularly if you have a large amount of RAM, and during this time the hard drive is still spinning - and writing data. If you want your Mac to go to sleep straight away and don’t care about losing the ’safe’-ness of your sleep mode, you can change your hibernation mode using this terminal command:

sudo pmset -a hibernatemode 0

Before doing this, you might want to check what your current hibernation mode is:

pmset -g | grep hibernatemode

By default it will either be 3 (Safe Sleep) or 7 (Safe Sleep if you have secure virtual memory enabled).

Now your Mac should go to sleep much quicker.