How on earth to fix this

[Peteey]

Details changed as outing

So I was away for 3 weeks on an unavoidable one off work trip. I video called DS (4) every day. My other half did a great job of getting DS to and from nursery and keeping him fed and happy, but didn't bother with the bedtime routine and let DS fall asleep whenever he felt like it.

DS usually sleeps 7pm until 7am and was a calm, easygoing child. Instead DS is now sleeping 11pm until 5am and is ratty, tearful, and is behaving like a (very exhausted) little terror.

He now won't sleep before 11pm or sleep in until after 5am even though I have put him straight back on his previous bedtime routine.

I am tearing my hair out and will happily take any advice for getting back to sleeping a reasonable amount, as frankly 6 hours sleep a night is way too little sleep for him.

I would start a positive star chart type thing, get a few small prizes. Start putting him to bed a bit closer to 11 as his body clock has prob changed a little then slowly bring it forward as he loses the habit of battling bedtime. If he goes to bed (even at 10pm) with no battles then give him a star. Then slowly wean the bedtime earlier each night and bring his body clock back to 7-7. As he starts to sleep earlier the early riser should rectify itself

I think you will need to deal with this with patience and kindness, as DS must unfortunately have found the whole experience quite destabilising. I would tell him that you or his dad (assuming OH is his dad) will be sitting in with him from 7:30 after the usual bedtime routine with dim lighting, and a calm audiobook or music on, but if he gets up be firm in a kind way that he needs to get back into bed as it’s night time. I would read extra books at bedtime to extend the time to 7:30, to try to return him to a feeling of safety and predictability, and 7 may be too early for him now. Add some extra exercise outside in the afternoon. Once he feels calmer and reassured that the old boundaries are once more in place he will hopefully naturally sleep longer in the morning again.
Your OH has really let your DS down here at a time when he needed consistency, he’s not done a “great job” at all and I hope that’s obvious to him given the consequences.