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Low energy (lethargy) in cats

Black cat on white background


We all know our feline friends like to spend a lot of time sleeping. But would you be able to tell if their lethargy was a sign of a problem?

Always take your cat to the vet for a full check over if you are worried they are sleeping more than they should be, out of sorts or showing any other signs of illness.

Is it normal for my cat to sleep a lot?

Quite simply, yes it’s normal for cats to sleep a lot. Cats can sleep anywhere between 12-16 hours per day! Older cats and young kittens may even sleep more than this. But why do they spend so much time sleeping?

Cats naturally feel the need to conserve energy for hunting. Even our domesticated friends have that natural behaviour within them, so tend to sleep more during the day and become more active at night. This may explain why as you’re trying to sleep, you can often hear your cat racing around the house!

The following signs, at the same time as sleeping more may indicate a problem:

  • Grooming less than usual
  • Playing or exercising less
  • Personality changes
  • Being floppier than usual
  • Hiding away more than usual
  • Eating less or nothing at all
  • Being slow to respond to things going on around them (e.g. sounds, or if you stroke them).

When to contact your vet

Take your cat to the vet if you’ve noticed any signs of lethargy that don’t get better within 24 hours. The problem may be something minor but could be the sign of a more serious underlying condition.

You know your cat best. If they don’t have the symptoms listed above but you are still concerned it’s always best to contact your vet.

Why is my cat suddenly so lethargic?

Lethargy in cats can be a symptom of many different conditions. We’ve listed some of the more common causes below:


Just like humans, cats can pick up viruses that make them feel poorly and lethargic.


Arthritis is a painful condition of the joints that can make moving around difficult. Arthritis is much more common in older cats.


Being overweight puts extra strain on joints and the heart and often causes lethargy.

Bladder problems

Both cystitis (bladder inflammation) and bacterial cystitis (bladder infection or UTI) make a cat feel very unwell.

Kidney disease

Kidney disease causes waste products to build up in the bloodstream and make your cat feel very poorly. Kidney disease can come on quickly or gradually.


Diabetes often causes lethargy at the same time as weight loss and extreme hunger and thirst.


Anaemia is a low number of red blood cells - red blood cells transport oxygen around the body. Anaemia can cause your cat to feel weak and lethargic.


Stress in cats can lead to many health issues and can cause them to withdraw. Cats are quite prone to stress.

Heart disease

Heart problems lead to poor circulation and often causes lethargy.


Cancer, although much rarer than other causes in this list, often makes a cat feel lethargic (as well as many other symptoms).

Toxins or poisons

Exposure to toxins or poisons, rat poison for example, can cause severe illness (and be a possible cause of lethargy).

Published: October 2018

PetWise Pet Health Hub – brought to you thanks to support from players of People’s Postcode Lottery 

Written by vets and vet nurses. This advice is for UK pets only.

Illustrations by Samantha Elmhurst