Even if your child is fine with staying somewhere else during the day, night time can be a much bigger deal. Young children tend to be more clingy and it is difficult for them to suddenly adapt to a new routine away from home. If your child is eager and has spent nights away at a relative's house before, then the prospect of a sleepover will be fun, not traumatic.
If you have any doubts about your child's ability to behave normally at bedtime in someone else’s household, it’s probably best not to take the chance and commit to a sleepover. You can do a trial run, by arranging with a relative to have your child stay over for a few hours in the evening. Kit your child out with a sleeping bad, case and soft toys, to simulate the experience of sleeping over at a friend's house. Fetch your child after the normal bedtime and assess their attitude and behaviour. This is a good indication as to whether or not your child is ready for a sleepover.
If you do decide to let your child stay at a friend's house, make sure you meet the parents at the house and check that everything is safe and that there is nothing within reach that can harm your child, such as guns, knives or tools. Discuss any issues you feel are relevant with the host parents, such as what kind of movies or television shows you allow your child to watch. Take precautions if you think your child may wet the bed. Avoiding the inconvenience for the parents and discomfort for your child is worth the effort. Inform the friend's parents about any food restrictions, medical conditions, or special precautions to take with your child. Have your cellular phone on you when you leave and give them your number, in case of emergencies, or in case of separation tantrums.
Speak to your child before you leave and let them know you are coming back to fetch them in the morning. Calling your child just before bedtime can be reassuring, but can also trigger anxiety or a tantrum since you are reminding them that you are not there.
As far as sleepovers go for young children, it is ultimately your decision. Trust your instincts when it comes to the readiness of your child and whether you think the host parents are reliable enough to look after your child.