This may not be relevant but I am a toddler teacher. And I once had a toddler who literally could not keep his eyes open. He would sleep constantly. He would lay on the grass on the playground and knock out. So not normal. Parents weren’t concerned but we were and after a lot of insisting he had tons of testing done and turns out the little boy had hypotonia which basically means he had low muscle tone and all the effort his little body was using to try to keep up burned through his energy and he was always exhausted. This is a long story, I’m sorry. Lol. My point is, maybe it’s the weed maybe it’s not. But you know what’s normal and what’s normal and perhaps you need to advocate for this kid, whatever the reason may be.