Every night I have to lie in beside my 5-year-old daughter when she is going to bed until she falls asleep. We know this can’t continue, so we are wondering what is the best solution? Should we just put a mattress on our bedroom floor and let her come in to us if she wakes? We now have a 3 month old baby girl as well.
Children’s sleep is often disturbed by anxiety or insecurity. It may be that the birth of her sister has provoked an insecurity for your older girl, perhaps related to her sense of how she now fits in the family, since the family dynamic will have changed dramatically. It might be useful to explore this with her, guessing out loud about how you think she might feel (positively and negatively) about her sister.
Practically, regarding her sleep, there is nothing wrong with sleeping in her room, or having her sleep in with you, other than the disruption it might cause you. Helping her to get to sleep with the security that your presence provides is a good thing, in the short term, and is something that you can slowly wean her off over time, as things settle for your family.
Weaning will involve moving yourself, from being in the bed, to being beside the bed, then to being further from the bed and eventually to being outside the room and just coming in regularly to check on her. The weaning process can be gently achieved over a couple of months, giving her time at each stage to become accustomed to the increased distance and greater reliance on her own self-soothing.