Are you getting enough sleep at night? Sleep is when your body goes into rest and repair mode. It is the only time your body is able to actively "power down". Additionally, laying down reduces the pressure on the discs of your spine, allowing them to re-hydrate and expand.
Throughout the day the discs of your spine lose water and also lose height as the force of gravity acts upon us. At night, they are allowed to gain back this height and go through their own "rest and recovery" process. This process is very important because chronically dehydrated discs can undergo arthritic changes prematurely and lead to problems down the road.
So be good to your spine, brain, and body by getting enough rest at night! It will help you feel more energized the next day and lead to a happier and healthier life.