Toddlers shouldn't spend long hours alone in the their crib, whether they're crying to get out or playing happily. Young children need to spend time with other people, even if they might sometimes prefer a little down time without other people around. You know your baby and are the person best able to decide how long is too long when it comes to leaving your baby alone in bed.
Crying Before Bed
Even if you're a fan of the "cry-it-out" method of putting your child to sleep, you should set limits on the length of time that you leave your crying toddler in the crib. The limits you set may depend on your toddler; Infant Sleep Specialist Nicole Johnson recommends no longer than 30 minutes before getting him up and trying again in half an hour or so. The Family Education website recommends telling your toddler you'll check on him in five minutes, or whatever arbitrary time limit you decide upon. Then do so, without picking your child up or taking him out of the crib. An Australian study published in the October 2012 issue of "Pediatrics" showed that "crying it out" or other behavioral sleep techniques isn't harmful for children.
Happy in the Morning
If your toddler wakes up happy and willing to entertain himself with books or stuffed animals, you might happily entertain yourself for half an hour or so, or you might feel slightly guilty for leaving him in there, no matter how happy he seems. Even if your child seems happy alone in his crib, he still needs to spend time with you and the rest of his world more than he needs time alone. Before age 18 months, most babies won't want to spend time alone, according to pediatrician Dr. William Sears. That means your toddler might cry for you as soon as he awakes. If he does, don't leave him crying in the crib. But if he does start entertaining himself in the crib in the morning, Ms. Johnson says there's no harm in leaving him alone for up to 45 minutes as long as he's happy.
If your toddler is happily playing in the crib before he falls sleep or wakes up happy in the morning and plays for a bit before calling for you, he's learning to entertain himself. Spending time alone gives him a chance to use his imagination and to learn the joys of spending time with the pleasure of his own company. Some toddlers, like some adults, need to wind down quietly by themselves before bedtime; you might hear him singing to himself, laughing or talking to his stuffed animals to put himself to sleep. Try to limit his "down" time to 20 to 30 minutes before naps and 30 minutes before bedtime, Ms. Johnson recommends.
If your toddler is miserable, it's never a good idea to leave him screaming in his crib for hours, even if it's bedtime. He might be overstimulated from a busy day and need more unwinding time with you, or if he still takes a nap, he might have slept too long or too late to go to bed at his usual time. Too much time "resting" in bed in the morning could also delay his afternoon nap and throw off his entire days' schedule. If your child has reached climbing age, being alone too long in his crib could tempt him to practice his skills on the crib rails, which could lead to injuries from a fall. Once your child can stand, put the crib mattress at the lowest height to make it more difficult for him to reach the rail.