Meditation increases attention and prefrontal cortex activity, which may inhibit the ability to fall asleep.

“So meditation is actually, it has a high attentional load. It requires a lot of prefrontal cortical activity that's involved in attention. Which then logically relates to one of the outcomes of this study which is that attention ability is improved in daily meditators. It also points out that increasing the level of attention and the activity of your prefrontal cortex may, and I want to emphasize may, because here I'm speculating about the underlying mechanism, inhibit your ability to fall asleep.”