18 to 36 Months
By 18 months, most babies have given up their morning nap; at 3, some will be ready to give up their afternoon nap as well. At this stage, there is so much excitement in a toddler's life that she can't wind down at night, even when she's exhausted. If you find that your toddler has a cranky period toward the end of the day, it may be a sign that she needs to go to sleep earlier. "Well-rested children don't behave like that," notes Dr. Weissbluth.
Children often wind up in your bed at this age as a result of two major developmental milestones: Instead of just crying, they can now actually call out "Mommy" or "Daddy," which is a lot harder to ignore; and the move into a big-kid bed means they don't even need to call -- they can just show up at your bedside. Anat Schecter's older son, Jake, made it into a game. "We'd put him in, he'd run out, we'd put him in, he'd run out," says his mom. "This could go on for as long as an hour. So I ended up sitting outside the bedroom door. Whenever Jake left the room, I would walk him back to bed. This went on for several weeks until he realized that we weren't going to give in."