16 month old spends the majority of the night right at the top of his cot to thr point where he bangs his head. Throughout the night we have to pull him down numerous times. If we don't pull him down he will grunt and groan until he wakes himself up and then not fall back asleep. This morning was 415am and yesterday 5am. Absolutely knackered. He is quite tall at 85cm but still looks like there is space for him. He has a cot not a cot bed (120cm x 60cm) Debating on buying a cot bed as out of options. Any advise would be lovely.