If you’ve followed this blog for a while, you’re likely no stranger to the concept of sleep regressions. You've probably experienced them first-hand, right? ;) If you’re new here, however, let us fill you in. A sleep regression refers to a period of time when a baby or toddler who’s been sleeping well suddenly begins waking at night and during naptime or even refusing to go to sleep at all. There are several distinct regression phases that most babies and toddlers experience: one at 4