There are several potential causes of your dog barking while sleeping. Some of these include: A bad dream Insomnia (barking as a result) Loud noise from outside Boredom So, let's take a look at each of these factors individually. The first thing to consider is whether your dog is actually dreaming during this time. This is the most popular theory behind why dogs bark while sleeping. They may just be dreaming about something that they saw earlier in the day. For example, if your dog was playing with another dog, and then they both fell asleep in the same bed, they may be dreaming about that experience. But this doesn't apply to all dogs. Dogs that are highly intelligent, like Border Collies, are known to bark during their dreams, but this isn't always the case. Another possibility is that they are suffering from insomnia. The National Sleep Foundation estimates that approximately 30% of people suffer from some form of sleep disorder. If your dog is barking excessively, it's possible that they are also experiencing this issue. This is particularly relevant if your dog is a puppy. Puppies need around 16 hours of sleep per day, which means that they should only be woken up once in the evening.