George Washington was Supposed to be over 6’ tall also. If you see his bed in Mount Vernon and his clothes, you begin to have doubts. If he fit into the clothes, they had to have been elastic and if he slept in the bed, a full quarter of him rested on the floor.
Medieval beds are also small, but most illustrations of them show people slept in a reclining position, rather than laying down. I don’t know if that held true in GW’s day.
Colonials did not sleep lying all the way down like we do today. They slept with their heads and shoulders up, mostly due to respiratory ailments. They didn’t have our medicines and it made it easier breathing at night.