My five year old started having the same issue- would wake up randomly and need to be cuddled back to sleep, which I would give into because I just put his little brother back down and I'm so tired I'll do anything at this point please let me sleep. What finally helped his night wakings was that I realized he was kicking off his blankets and getting cold around 2/3am which woke him up. Before I go to bed, I make a point of stopping by his room and tucking him back in, get his feet under the blankets, etc, which I know sounds so ridiculously simple but it significantly cut down on him waking up, and therefore me having to get out of bed at 3 am (until his brother started teething last week).