Nightmares are scary dreams that awaken children and often make them afraid to go back to sleep. They usually occur during the REM (rapid eye movement) period which happens during the last third of sleep and so are most common in the very early hours of the morning. Although adults also experience nightmares, because young children are learning new information and absorbing new experiences at an exceptionally rapid rate, they are more prone to bad dreams and waking up during the night.
From about the age of 6 months, it is normal for children to have the occasional bad dream. For example a toddler going to kindergarten for the first time may have nightmares about being separated from his or her parents. The older child may have nightmares about real dangers or even death.
Children waking from a bad dream are usually fully conscious and aware of their surroundings, although they may be a little confused and obviously upset. This can be very distressing for both parent and child and the interrupted and disturbed sleep that can result often leaves everyone feeling groggy the next day.