Bags are packed, clothes are ready and food is prepared.
The night before whatever is planned for the new day everything is organised and in its place so that there is the least resistance to executing that plan. 
If there is at all the slightest pain point to moving forward and out of bed early the brain will seize this opportunity and make you pay for it.
Ie in the form of going back to sleep.
So just have all your ducks in a row before hitting your head to pillow, you’ll be stoked you did.