DS 20months now hates bed

[miabl2]

My DS who is now 20 months has always been brilliant at going to bed. Watches TV for 30 mins and then goes to cot awake at 7pm. Since Friday night he has cried whenever it is time to go to bed this includes daytime nap. Any ideas as to why the sudden change and what I can do to get my calm evenings back!

Maybe he feels trapped in his cot, our DD1 started to resist her cot at about this age and slept much better when we took the side off and she knew that she could get out. Thankfully she has only occasionally used her new freedom to wander about, in general she stays in bed.