MeditationBodyPosture

In my experience, good body posture is optional in Zazen and Dzogchen style Meditation. It can make meditation easier, but it is not a primary factor. As long as the body is in a posture that is stable, and that does not make you drowsy, it will serve as a good basis for meditation.

However, sitting with a straight spine can certainly enhance focus. Touching your tongue on the roof of your mouth reduces the accumulation of saliva and the need to swallow, which can become distracting. And having good posture can prevent discomfort and injury.