Sudden sleep problems, 4yo!

[Sunflower30]

Just wondered if anybody had experienced this, my 4yo super sleeper is suddenly not sleeping well at all. He's been sleeping independently since about 5 months old. goes to bed 7ish, I have a cuddle and chat for 5 minutes, night light on, goes to sleep and wakes at around 7/7.30. He is suddenly very clingy and seems anxious (although he can't say why), cries if I leave him. He basically wants me to stay in bed with him til he sleeps. Then he wakes at some point in the night, at varying times and gets in bed with me. If I try and take him back he cries and screams. I have an 18mo too and live in a semi so im conscious of causing too much fuss at that time.
Any ideas what it could be? Or ways to improve the situation? He's not swayed by treats at all on this.

[MoonlightMedicine]

We went through this with my DS and put it down to a phase of separation anxiety. It did pass fairly quickly I think.

[GothicRainbow]

We're going through it now with our three year old DS. At bedtime we are happy to sit in his room with him and wait until he goes to sleep - usually only 15mins. He's waking in the night usually once and we can now just pop him back to bed, explain its still night time (gro clock helps with this) give him a kiss and say we are across the hall if he needs us.

If he's particularly anxious we have a mattress in his room we can pull out and sleep on his floor. Means everyone gets sleep (we have a 3.5 month old DS2) so try to avoid crying if at all possible!