For example, the distance between Mercury and Earth can range from 77 million kilometres at their closest point, to 222 million kilometres at their farthest.
From ages 1 to 3, most toddlers sleep about 12 to 14 hours over a 24-hour period. Separation anxiety, or just wanting to be up with mom and dad (and not miss anything), can motivate a child to stay awake. So can the simple toddler style of always saying No!.
For more information on helping your baby sleep well, including how to encourage him to soothe himself to sleep, check out sleep basics for babies ages birth to 3 months, 3 to 6 months, 6 to 9 months, and 9 to 12 months. To help your toddler establish healthy sleep habits, read our articles on 12- to 18-month-olds and 18- to 24-month-olds.