There can be many sources to sleep troubles in toddlers e.g. - sleeping without parents, sleeping in unfamiliar places, absence of routine, no ability to calm oneself, etc. The answer is associated with the source. Good detective work and a commitment to support what is helpful to developing adequate sleep routines for toddler and others in the home is needed. For example, toddlers sleeping with their parents may need to move in bearable bit toward their own bed. Having parents sit by their bed until they sleep is a good start to transitioning. Always let your child know that you will be leaving once they are asleep so they do not wake up to a surprise. For a child who struggles to calm themselves, something as simple as determining soothing sounds to play at bed time may be the fastest answer. If this does not work, then more investigation is needed to determine the reason for difficulty with self-soothing.