Sleep and rest are so so so under rated in a good training regimen! Without these key features you are very unlikely to progress and move forward and here is why!
Just like a computer your body needs to shut down and reboot to process your day mentally but also to heal after the beating your workouts put on the body. Micro tears form in the muscle tissues and therefore need to heal so you can get stronger! No rest = no healing = no strength gain = higher risk of injury.
To clean out the toxins! You put foods in your body each day and whether they are healthy or not your body must clean out toxins from unhealthy foods as well as the chemicals, free radicals, and other harmful elements we come into contact with each day!