If you wake up tired, restless, or unrested even after a full night's sleep, position might be part of the problem, and it's one of the quieter pieces most people overlook. Side sleeping supports breathing and digestion, back sleeping works against you if you snore, and stomach sleeping offers the fewest benefits of the three. Add a sleep mask to block out light, and you've covered two of the biggest external factors working against good rest. But there's a third piece, what your nervous system actually needs internally to power down, and that's where the story doesn't end with your sleep setup.