Why does my dog sleep so much?

Dogs sleep a lot more than humans — this often surprises new owners. But knowing what is normal for your dog's age and breed helps you spot when something might be wrong.

What is normal sleep for dogs?

- Adult dogs: 12–14 hours per day on average
- Puppies: 16–20 hours per day — sleep is when the brain processes new experiences and the body grows
- Senior dogs: up to 18–20 hours per day as metabolic rate slows and joints become less comfortable
- Large and giant breeds (Mastiff, Saint Bernard, Great Dane): naturally sleep more than terriers and working breeds
- Sighthounds (Greyhounds, Whippets): sleep very long periods between short, intense bursts of activity

A dog that sleeps a lot but is bright and enthusiastic when awake — plays normally, eats well, and engages with you — is almost certainly fine.

When extra sleeping is a concern

The key is a change from your dog's normal pattern — sudden increase in sleep, combined with any of:

- Lethargy (different from sleepiness): a lethargic dog is difficult to rouse, uninterested in food or play even when awake, and mentally dull
- Loss of appetite: any dog that is not eating normally for more than 24 hours needs attention
- Weight loss: sleeping more because the body is fighting illness
- Increased thirst or urination: signs of metabolic disease (diabetes, kidney disease, Cushing's)
- Reluctance to move or stiffness on waking: arthritis, disc disease, or generalised pain
- Exercise intolerance: a dog that tires very quickly on a walk may have cardiac or respiratory disease rather than laziness
- Mood changes: less interactive, seems flat or withdrawn

Common medical causes of increased sleep

- Hypothyroidism (low thyroid hormone) — classic presentation: weight gain, exercise intolerance, cold intolerance, dull coat, sleeping more
- Anaemia — reduced red blood cells mean less oxygen delivery; the dog tires easily
- Infection or systemic illness — fever drives sleep as the immune system works
- Pain — a dog in chronic pain conserves energy by moving and engaging less
- Medication side effects — many drugs cause sedation (antihistamines, gabapentin, steroids)

What to do

If the increased sleep is new and accompanied by any of the above signs, a vet check with basic bloodwork will usually identify or rule out the most common causes within a single visit.