SYMPTOM
Sleeping more than usual
The dog or cat spends noticeably longer stretches asleep or dozing, is slower to rouse for meals, greetings, or a walk, and initiates play, exploration, or affection less often than before. Owners often describe it as the animal simply not being themselves during what would normally be an active part of the day.
Degenerative Joint Disease
Osteoarthritis in dogs and arthritis in cats make rising, stretching, and moving around less comfortable, so the animal increasingly chooses rest over activity. Sleep often increases first after exercise or in cold, damp weather, and may be accompanied by stiffness on rising or a reluctance to jump.
Chronic Kidney Disease
Reduced kidney function allows waste products to accumulate in the bloodstream, producing a generalised malaise that is often first noticed as increased sleep and reduced enthusiasm. This is particularly relevant in older cats, and in dogs the risk rises with age across breeds rather than being confined to larger dogs, tending to build gradually alongside increased thirst and urination.
Endocrine Imbalance
Hypothyroidism in dogs slows the metabolic rate, and one of its more consistent early signs is a dog that seems to need more sleep and tires more easily on walks. Weight gain despite a stable diet and a duller coat often accompany the change.
Cognitive Decline
Canine and feline cognitive dysfunction can alter the sleep-wake cycle itself, so daytime sleep increases while night-time settling becomes less predictable. This pattern tends to build slowly over months in older animals and often accompanies other subtle shifts in orientation or routine.
Anaemia
A falling red blood cell count, whether from immune-mediated destruction or another cause, reduces the oxygen reaching tissues and produces fatigue that owners often read as excess sleepiness. Pale gums and a faster resting breathing rate can accompany more pronounced cases.
Adrenal Insufficiency
Addison's disease in dogs produces a waxing and waning malaise that is easy to mistake for simple tiredness, and in the substantial minority of affected dogs with the atypical form of the disease, routine electrolyte results can remain within normal limits throughout. Lethargy here can fluctuate rather than build in a straight line, sometimes alongside vague gastrointestinal upset.
Normal Age-Related Change
Many older dogs and cats simply sleep more as part of ordinary ageing, particularly when the extra sleep is stable, unaccompanied by other changes, and the animal remains bright, eats well, and rouses normally when called. A change in routine, activity level, or season can also shift the balance between waking and resting hours without reflecting an underlying process.
Why timing matters
Early observation
Sleep that has increased over days rather than months more often reflects an acute process such as infection, a pain flare, gastrointestinal upset, or a medication effect, and is more likely to resolve as the underlying trigger passes.
Later presentation
A gradual, long-standing increase in sleep that has built over many weeks or months more often reflects a chronic or degenerative process, such as joint disease, organ decline, or cognitive change, where the sleep pattern is one of several slowly accumulating shifts.
Tracking whether the change appeared abruptly, crept in steadily, or comes and goes in episodes helps separate a self-limiting event from a chronic process that is likely to continue developing, and this trajectory is often more informative than the sleep increase considered on its own.
Conditions commonly associated
Osteoarthritis in Dogs
Joint pain reduces willingness to move and makes rest the more comfortable option, so affected dogs often sleep more overall.
Arthritis in Cats
Discomfort in the joints, often under-recognised in cats, lowers general activity and increases time spent resting or asleep.
Chronic Kidney Disease in Cats
The buildup of metabolic waste products that accompanies declining kidney function produces a generalised lethargy that owners often notice first as increased sleep.
Hypothyroidism in Dogs
A slowed metabolic rate reduces energy levels and increases the amount of sleep a dog appears to need.
Canine Cognitive Dysfunction
Disruption of the normal sleep-wake cycle is a recognised feature, producing more daytime sleep alongside altered night-time settling.
Immune-Mediated Haemolytic Anaemia (IMHA)
A falling red blood cell count reduces oxygen delivery to tissues, producing fatigue that is often read at home as excessive sleepiness.
Addisons Disease in Dogs
Addison's disease leaves the adrenal glands unable to produce adequate cortisol and aldosterone, disrupting normal energy metabolism and electrolyte balance, so affected dogs tire more easily and spend more time asleep or resting.
When to explore further
A sudden shift into unusual sleepiness in a dog or cat that was previously consistently active carries different weight to a gradual drift that has developed over many months.
Increased sleep alongside a change in thirst, urination, appetite, or body weight tends to widen the list of relevant systems beyond simple tiredness.
Pale or unusually white gums, laboured breathing, or a reluctance to settle in one position noticed alongside increased sleep may benefit from characterisation rather than observation alone.
Cats in particular tend to reduce visible activity gradually and without obvious complaint, so a cat that has stopped jumping to favourite perches or grooming as often can be showing the same underlying pattern in a quieter form.
A reversal of the normal sleep pattern, where daytime dozing increases but night-time settling becomes more restless or vocal, points toward a different set of possibilities than simple daytime fatigue.
Noting the approximate number of hours spent active versus resting over a few representative days, along with the time of day sleep is heaviest, can add useful context. A short video of the animal rising from rest or moving after a period of sleep can capture stiffness or hesitancy that is easy to miss in the moment, and logging appetite, thirst, and body weight alongside the sleep pattern helps show whether the change is isolated or part of a broader shift.
Last reviewed: 27 August 2026 · Dr Alastair Greenway MRCVS