Sundowners Syndrome in Dogs: Signs, Sleep Changes and What Helps

Dog science for dog moms (and some dads)

Why older dogs doze all day and pace at night, how to spot canine cognitive dysfunction early, and what research says actually helps.

Last updated: November 2, 2026 · By the MrFluffyFriend Dog Science Team · 21 studies, all linked · How we researched this · 10 min read

✓Based on peer-reviewed science

This article is general information and does not replace advice from your vet.

The small blue numbers in the text (like ¹) link to the study behind that sentence. Tap a number to open the source. Every claim in this guide is based on peer-reviewed research.

Key takeaways

• Older dogs often nap more by day and wake more at night ^6,2.
• Restless nights, less interaction, getting lost at home and anxiety were the four signs that stood out in dogs with CCD ⁹.
• Signs of cognitive decline were found in 28% of 11 to 12-year-old dogs and 68% of 15 to 16-year-olds in one study ¹⁰.
• More active dogs had about half the odds of clinical CCD, but this link does not prove cause ⁴.
• In two follow-up studies, CCD did not shorten survival ^9,11.

Often, yes, but mostly in the daytime. When researchers recorded brain activity around the clock in four very old and four young lab dogs, the old dogs slept more during the day, were awake more at night and had much less REM sleep ⁶. That is a tiny study, but it fits what owners report.

In 28 senior family dogs recorded during an afternoon nap, dogs with higher dementia scores and poorer problem-solving spent less time in NREM and REM sleep, and their sleep looked shallower on the EEG ¹². If your main question is how much sleep is normal for an older dog, our guide why senior dogs sleep all day goes into the hours in detail.

An international group of experts defines canine cognitive dysfunction syndrome as a chronic, progressive, age-related brain condition with changes in several areas, summed up as DISHAA: disorientation, social interaction, sleep-wake changes, house soiling, learning and memory, activity changes and anxiety ¹.

"Sundowning" describes the late-day part of it. In the survey of 205 senior dogs, restlessness in the late afternoon and early evening tended to increase as cognitive decline progressed ².

Brain studies explain the Alzheimer's comparison. In 24 senior dogs examined after death, amyloid-beta deposits resembled early Alzheimer's changes, with more amyloid in dogs that had cognitive problems ⁷. Reviews describe Alzheimer-like brain changes in dogs with CCD as well ¹³.

• In 180 dogs aged 11 to 16, 28% of 11 to 12-year-olds and 68% of 15 to 16-year-olds had changes in at least one area, such as the sleep-wake cycle ¹⁰.
• In 325 dogs older than nine, 22.5% showed signs of cognitive impairment, and both how often and how severe rose with age ¹⁴.
• In 15,019 dogs from the Dog Aging Project, each extra year of age raised the odds of CCD by 52% ⁸.

Body size matters too. In survey data from more than 15,000 dogs, dogs over 30 kg started to show behavioral ageing two to three years earlier but declined more slowly, and larger dogs had a lower CCD risk in the oldest age group ¹⁵.

In a Danish study that followed 94 older dogs, four signs stood out in dogs with CCD: sleeping during the day and restless at night, less interaction, disorientation at home, and anxiety ⁹. Watch for:

• Pacing, panting or waking you at night, especially in the small hours ².
• Wandering aimlessly or staring into space ¹¹.
• Avoiding being petted or showing less interest in you ^11,9.
• Getting up at night to pee or poop in a house-trained dog ².
• New anxiety, for example in the evening ^9,2.
• Bumping into things or responding less to sounds: these were reported more often in severe CCD ².

Changes often creep in slowly. In 51 dogs followed for two years, a third of dogs with normal cognition developed mild impairment, and the speed of decline varied a lot between dogs ¹¹.

CCD is diagnosed by ruling out other causes. The expert guideline asks for a physical, orthopedic and neurological exam and lab work first ¹. Common culprits include:

• Pain. In dogs with osteoarthritis, owners rated aspects of night-time sleep as better on a vet-prescribed anti-inflammatory pain medicine than on placebo, even though activity monitors did not change ¹⁶.
• Failing senses. Dogs with both vision and hearing loss were far more likely to be reported as cognitively impaired (79 to 94% versus 25 to 27%), though the study could not say which causes which ¹⁷.
• Other illness. Neurological, eye and ear disorders were linked to higher odds of CCD in the Dog Aging Project ⁸.

1. Keep days active. In 11,574 dogs, more physical activity went with milder signs, less worsening over six months and lower odds of clinical CCD ⁴. Adjust walks to what your dog can comfortably do.
2. Keep learning. In a two-year study, aged lab beagles given behavioral enrichment learned better than those without it ⁵. Short sniffing games and simple tricks count.
3. Try a class. In 42 dogs with mild to moderate CCD, five weekly classes kept CCD scores stable; dogs in physical training classes slept slightly better and owners felt less burdened. There was no untreated comparison group ¹⁸.
4. Ask about diet. In a placebo-controlled trial of 87 dogs, dogs on a diet with 6.5% medium-chain triglyceride (MCT) oil and a nutrient blend improved in all six groups of signs after 90 days, while the control group improved in four ¹⁹. The diet was developed by the researchers' own company. Discuss any diet change with your vet.
5. Start early. A recent review recommends combining medication where needed, nutrition and enrichment, and stresses early intervention ¹³.

This is one of the most searched questions, and the research is more reassuring than many owners expect. In a Danish study that followed 94 dogs over 8 years old for up to about four years, CCD did not shorten survival, and the authors concluded that dogs with CCD seem to have a good chance of living a full lifespan if supported by the vet and the owner ⁹.

A second study of 51 older dogs, followed for two years, also found that a CCD diagnosis did not affect survival, even though signs got worse over time in the dogs that had it ¹¹. Both studies are small, so they cannot give an exact number of months or years for your dog.

Book a check-up if your senior dog shows new night waking, confusion, accidents or anxiety. Owners often put these changes down to normal ageing, which delays recognition ²¹, and most affected dogs in one survey had no diagnosis ³. Bring a short diary of sleep, night waking and accidents. A few simple questions about sleep, interaction, confusion and anxiety can already flag CCD ⁹.

Your questions, answered

CCD

Canine cognitive dysfunction: a chronic, progressive, age-related brain condition with changes in behavior and sleep ¹.

DISHAA

Disorientation, interaction, sleep-wake changes, house soiling, learning and memory, activity, anxiety ¹.

REM sleep

The sleep stage linked to dreaming; it is reduced in very old dogs ⁶.

Amyloid-beta

A protein that forms deposits in ageing brains, in dogs and in people with Alzheimer's disease ⁷.

Related reading

• Why does my senior dog sleep all day?
• How many hours do dogs sleep?
• Caring for a dog with arthritis at home

Every source is a peer-reviewed paper. Tap a link to open the abstract (PubMed) or the publisher's page (DOI). Labels show the study type; amber labels mark weaker or indirect evidence.

1. 1

   Olby NJ, Araujo JA, Gruen ME et al. The Canine Cognitive Dysfunction Syndrome Working Group guidelines for diagnosis and monitoring of canine cognitive dysfunction syndrome. J Am Vet Med Assoc. 2026.

   Expert guideline PubMed 41442884 DOI 10.2460/javma.25.10.0668

2. 2

   Taylor TL, Tuke J, Hazel SJ. Sleep-wake disturbance in canine cognitive dysfunction: Guardian-reported patterns and a practical screening tool. Vet J. 2026.

   Owner survey, 205 dogs PubMed 42571817 DOI 10.1016/j.tvjl.2026.106817

3. 3

   Salvin HE, McGreevy PD, Sachdev PS et al. Under diagnosis of canine cognitive dysfunction: a cross-sectional survey of older companion dogs. Vet J. 2010.

   Owner survey, 497 dogs PubMed 20005753 DOI 10.1016/j.tvjl.2009.11.007

4. 4

   Bray EE, Raichlen DA, Forsyth KK et al. Associations between physical activity and cognitive dysfunction in older companion dogs: results from the Dog Aging Project. Geroscience. 2023.

   Cohort study, 11,574 dogs PubMed 36129565 DOI 10.1007/s11357-022-00655-8

5. 5

   Milgram NW, Head E, Zicker SC et al. Learning ability in aged beagle dogs is preserved by behavioral enrichment and dietary fortification: a two-year longitudinal study. Neurobiol Aging. 2005.

   Laboratory beagles PubMed 15585348 DOI 10.1016/j.neurobiolaging.2004.02.014

6. 6

   Takeuchi T, Harada E. Age-related changes in sleep-wake rhythm in dog. Behav Brain Res. 2002.

   Lab sleep study, 8 dogs PubMed 12385805 DOI 10.1016/s0166-4328(02)00123-7

7. 7

   Alsulami A, Bogdani M, MacLean EL et al. Alzheimer's disease neuropathological characterization of the dog brain and relationship to biofluid biomarkers and cognitive function. NPJ Dement. 2026.

   Brain tissue study, 24 dogs PubMed 42845905 DOI 10.1038/s44400-026-00141-4

8. 8

   Yarborough S, Fitzpatrick A, Schwartz SM et al. Evaluation of cognitive function in the Dog Aging Project: associations with baseline canine characteristics. Sci Rep. 2022.

   Cohort study, 15,019 dogs PubMed 36008509 DOI 10.1038/s41598-022-15837-9

9. 9

   Fast R, Schütt T, Toft N et al. An observational study with long-term follow-up of canine cognitive dysfunction: clinical characteristics, survival, and risk factors. J Vet Intern Med. 2013.

   Cohort study, 94 dogs PubMed 23701137 DOI 10.1111/jvim.12109

10. 10

    Neilson JC, Hart BL, Cliff KD et al. Prevalence of behavioral changes associated with age-related cognitive impairment in dogs. J Am Vet Med Assoc. 2001.

    Owner interviews, 180 dogs PubMed 11394831 DOI 10.2460/javma.2001.218.1787

11. 11

    Schütt T, Toft N, Berendt M. Cognitive Function, Progression of Age-related Behavioral Changes, Biomarkers, and Survival in Dogs More Than 8 Years Old. J Vet Intern Med. 2015.

    Cohort study, 51 dogs PubMed 26463980 DOI 10.1111/jvim.13633

12. 12

    Mondino A, Catanzariti M, Mateos DM et al. Sleep and cognition in aging dogs. A polysomnographic study. Front Vet Sci. 2023.

    Lab sleep study, 28 dogs PubMed 37187924 DOI 10.3389/fvets.2023.1151266

13. 13

    Dondi M, Bianchi E, Borghetti P et al. Evidence-Based Clinical Management of Canine Cognitive Dysfunction Syndrome: Diagnostic Algorithms, Practical Guidelines, Critical Appraisal of Biomarkers and Translational Limitations. Animals (Basel). 2026.

    Review PubMed 41976093 DOI 10.3390/ani16071114

14. 14

    Azkona G, García-Belenguer S, Chacón G et al. Prevalence and risk factors of behavioural changes associated with age-related cognitive impairment in geriatric dogs. J Small Anim Pract. 2009.

    Owner interviews, 325 dogs PubMed 19200264 DOI 10.1111/j.1748-5827.2008.00718.x

15. 15

    Turcsán B, Kubinyi E. Differential behavioral aging trajectories according to body size, expected lifespan, and head shape in dogs. Geroscience. 2024.

    Owner survey PubMed 37740140 DOI 10.1007/s11357-023-00945-9

16. 16

    Knazovicky D, Tomas A, Motsinger-Reif A et al. Initial evaluation of nighttime restlessness in a naturally occurring canine model of osteoarthritis pain. PeerJ. 2015.

    Placebo-controlled study, dogs with arthritis PubMed 25722957 DOI 10.7717/peerj.772

17. 17

    Hopper RG, Bromberg RB, Salzman MM et al. Dual sensory impairments in companion dogs: Prevalence and relationship to cognitive impairment. PLoS One. 2024.

    Cross-sectional study PubMed 39413072 DOI 10.1371/journal.pone.0310299

18. 18

    Taylor TL, Tuke J, Fernandez EJ et al. Group training classes for dogs with canine cognitive dysfunction: effects on sleep, activity, and caregiver burden. Geroscience. 2026.

    Small trial, 42 dogs, no control group PubMed 42126808 DOI 10.1007/s11357-026-02309-5

19. 19

    Pan Y, Landsberg G, Mougeot I et al. Efficacy of a Therapeutic Diet on Dogs With Signs of Cognitive Dysfunction Syndrome (CDS): A Prospective Double Blinded Placebo Controlled Clinical Study. Front Nutr. 2018.

    Controlled feeding trial, 87 dogs PubMed 30619873 DOI 10.3389/fnut.2018.00127

20. 20

    Pavlin D, Hlebec V, Doušak M et al. The hidden cost of caring: Psychological burden among caregivers of dogs with cognitive dysfunction, cancer, and age-related decline. Vet J. 2026.

    Survey, 516 owners PubMed 41314458 DOI 10.1016/j.tvjl.2025.106510

21. 21

    Balatonfüredi V, Kubinyi E. Canine Cognitive Dysfunction from the Perspective of Dog Owners: Recognition, Care, and Emotional Challenges. Animals (Basel). 2026.

    Interviews, 22 owners PubMed 41976095 DOI 10.3390/ani16071117

MrFluffyFriend Dog Science Team

We read the research so you can make calm, informed choices for your dog. Every number in this guide was checked against the original study, and every study is linked above.

Last updated: November 2, 2026

This article is general information, not veterinary advice. If your senior dog suddenly sleeps much more, is restless at night, seems lost at home or has accidents indoors, talk to your vet.