Ok so I have a 19MO adopted daughter. She came to us at 9MO. She can be a strong willed, cheeky and a tad whingy little monkey like any self respecting 19MO 
but on the whole she slept brilliantly and without a fuss pretty much from when we got her .... that was until about a week or 2 ago. She's now being an absolute nightmare at sleep times. She refuses to nap in her bed and just runs back out, cries, generally messes about or does a poo right between falling asleep 
(yes I know the last one almost certainly wasn't deliberate but I felt that it deserved a mention haha) I've now resorted to driving her out for her naps which is fine but boring (as she sleeps for sometimes over 2 hours) and going to cost me a fortune as I just have to go to costa drivethru 🙈 She is then refusing to sleep at night as well. Normally she would've gone to bed at 7-7:30, maybe shuffled around a bit for half an hour max and then out. Now she's running out of her bedroom and me or DH have to stay with her until she falls properly asleep and that's often taking until around 9. I believe it's possibly a bit of her learning to be a bit cheeky and exert her freewill as she's seeing it as a bit of a game and sometimes giggling and running back to bed when we come back in the room to tell her to. However, I also believe it's a little bit separation anxiety as if we try and leave the room when she seems asleep but we're too quick she'll wake up with a start and get quite distressed.I will be fair and say that once she's asleep she is still sleeping well generally through the night. I know sleep regressions are common at around the 18 month mark but it's just totally caught us off guard. The general advice seems to be don't change too much and don't 'regress' with sleeping props. However especially with her being adopted I'm a bit loathed to not stay with her whilst she's trying to sleep if she's telling us she needs it even if she's taking the michael a bit. If we have to sit with her to fall asleep til she's 21 then sobeit that's the commitment we made but if anyone has any advice on how to gently train her out of it I'd be very interested. I'm also interested how long most people's 19MOs nap? Another thing I've considered is only allowing a slightly shorter nap (maybe 1 hour rather than 2-3 hours) but I don't know if that will cause overtiredness and make things worse. Finally did anyone who's kids went through similar find that it was only temporary? She has recently had hand foot and mouth so hoping it's just this that's caused her some temporary problems. Thanks xx