Is mindfulness meditation an effective method to fall asleep? It's my understanding that brain activity in the prefrontal cortex is suppressed during sleep and that mindfulness stimulates activity in that region. Based on this, it seems counterintuitive to think that the average person who is lying in bed and using mindfulness meditation reduces his/her sleep latency. Is there any empirical indication or theoretical argument either way?
**Is there any empirical evidence meditation is good for sleep? **

Yes. There is. But it definitely depends on the type of meditation. Some types of meditation increase alertness. A few articles I found mentioned a study based on this, but failed to link properly. 

The below link is the empirical evidence. 
Mindfulness Meditation and Improvement in Sleep Quality and Daytime Impairment Among Older Adults With Sleep Disturbances

This second study demonstrates that people who meditate may need less sleep. I don't know if that qualifies for you. 
Meditation acutely improves psychomotor vigilance, and may decrease sleep need.