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Dogs and Sleep: The Forgotten and Underestimated Need


Date: June 1, 2023

How to cite: Barata, R. (2023). Dogs and Sleep: The Forgotten and Underestimated Need. Human-Animal Science.


What is the circadian rhythm in dogs?

The circadian rhythm in dogs refers to the natural, daily cycle of hormone levels in their blood. Specifically, studies have shown that the circadian rhythm of serum cortisol follows a 24-hour periodicity in adult female beagle dogs. In contrast, puppies do not yet possess a fully developed circadian rhythm in serum cortisol (Palazzolo & Quadri, 1987). Moreover, salivary cortisol, a measure of free cortisol, also exhibits a circadian rhythm that aligns with the serum cortisol rhythm in dogs. Typically, cortisol levels in dogs rise at sunrise and peak during the middle of the photophase (The period of light during a day-night cycle), with the highest serum cortisol concentration occurring between 10:00 a.m. and 12:00 p.m. in adult dogs.


The body core temperature in dogs follows a circadian oscillation, with the temperature highest in the afternoon and peaking one hour before lights off. Also, it has been observed that salivary cortisol in dogs peaks at the end of the photophase under a natural light-dark cycle (Giannetto et al., 2014). The paper also showed a substantial similarity between the trend of salivary and serum cortisol concentrations in dogs, where salivary cortisol decreases during the scotophase (The dark phase in a cycle of light and darkness) and increases during the light phase. Clock genes, known to regulate the circadian rhythm in mammals, are believed to play a role in controlling circadian rhythms in dogs. In particular, per1 mRNA, induced explicitly by glucocorticoids, has been identified as a potential molecular marker for monitoring circadian rhythms in dogs due to the demonstration of a circadian rhythm in canine PBMCs (peripheral blood mononuclear cells) associated with per1 expression. Consequently, per1 may serve as a useful molecular marker for analyzing circadian rhythms and studying the effects of drugs on clock genes in dogs (Ohmori et al., 2013).


How does the circadian rhythm in dogs affect their behavior?

The circadian rhythm in dogs influences their behavior in several ways. Dogs are polyphasic sleepers (multiple sleep bouts throughout the day), mainly during the night. They exhibit a diurnal circadian rhythm, most active during the light period. The paper from Schork et al. (2022) showed that:


  • Sleep structure can be influenced by sex, age, activity level, and environmental conditions.
  • Pre-sleep activity can improve sleep quality, while disrupted sleep patterns can lead to reduced motivation and daytime activity.
  • Dogs tend to be more active during the day and sleep more at night in domestic settings.
  • Longer sleep duration decreases behavioral expression and increases eating time. 
  • Sleep duration also serves as an indicator of welfare in shelter dogs.
  • Disrupted sleep patterns can have negative implications for dog well-being.


A Powerful Therapy Ally

Sleep plays a vital role in maintaining dogs' physical and cognitive health. It is crucial for immune system regulation, metabolism, cognitive well-being, and joint health. 


Furthermore, sleep is fundamental for cognitive homeostasis, particularly regarding memory consolidation and learning processing. (Bódizs et al., 2020; Mondino et al., 2023) By studying sleep in dogs, we can gain valuable insights into its significance and overall impact on their well-being. This makes them an excellent non-invasive translational model for sleep research.


Deprivation of sleep in dogs can harm their physical and mental health. Research has demonstrated that sleep loss disrupts activity patterns, increases anxiety-like behaviors, impairs cognitive performance, and is associated with depressive states (Bódizs et al., 2020; Tooley & Heath, 2022).


Some trainers and owners prioritize expending a dog's energy through various physical exercises, such as tug-of-war and chasing activities. It is crucial to address the misconception surrounding domestication, as it does not imply taming a species solely to adapt to human schedules within an apartment setting. The inherent nature of every organism is to conserve energy rather than expend it unnecessarily. Employing human routines to schedule exercises, manipulating instinctual drives, and prematurely ceasing activities based on the dog's perception of satiety rather than its actual needs can prove more detrimental than beneficial, based on my experience. Issues concerning under or over-stimulation cannot be resolved solely through physical exercise, which may affect the dog's sleep quality day and night. 


Moreover, the findings of my empirical research to achieve successful results in our behavior modification programs elucidate the significant correlation between the improvement in dog's lifestyle by the integration of olfactory stimulation, participation in long walks, and commitment to appropriate rest and sleep practices, as opposed to practices that involve excessive reliance on physical exercise activities and overstimulation techniques like ball throwing and tug games, as well as insufficient sleep routines (e.g., leaving lights on, lack of solitary sleep, within others).


Best Practices

Allowing the dog to sleep alone confers several benefits, warranting consideration. Two primary reasons justify this approach: firstly, external disturbances, such as movements and sounds caused by third parties, diminish the likelihood of the dog being awakened at night (Adams & Johnson, 1993). Secondly, it is an exceptional supplement in mitigating issues commonly reported as dog home-alone problems (Abrantes, 2015).


Electromagnetic radiation (EMR) exposure can adversely affect sleep patterns in humans and animals and induce various endocrine, health, and behavioral changes (Earth and Life Studies et al., 1993; Reif et al., 1995). In a study conducted by Hart et al. (2013), dogs were observed to align their defecation behavior with the Earth's magnetic fields, a form of natural electromagnetic field (EMF). This finding led the researchers to infer that continuous exposure to artificial EMFs may influence dogs' defecation behavior and other general behaviors. Taking steps to reduce exposure to EMFs, such as keeping dogs away from main electrical sources and turning off routers and other radio frequency (RF) devices during the night or when not in use, including an EMF inspection to identify potential sources of EMF exposure in-home, can be beneficial in improving sleep for both dogs and humans.


The secretion of melatonin, a hormone synthesized by the pineal gland, is profoundly influenced by exposure to darkness, thereby exerting a substantial impact on mammalian sleep. Referred to as the "hormone of darkness," melatonin is released in response to the absence of light. This hormone is produced during periods of darkness in diurnal (day-active) and nocturnal (night-active) animals, and its nocturnal secretion plays a pivotal role in regulating sleep patterns. Light has been demonstrated to significantly modulate melatonin secretion, with day-night light cycles altering its release rhythm. Optimal production and regulation of melatonin and the consequent enhancement of sleep patterns and overall well-being can be achieved through exposure to complete darkness (Masters et al., 2014). Therefore, promoting a totally dark environment will improve your dog's sleep.


Conclusion

The significance of sleep in canines and humans and its profound impact on their comprehensive health and general welfare is a fundamental matter. Based on my empirical research and professional experience, I highly suggest that all behavior consultants thoroughly review the criteria used in their dog behavior evaluations. Also, it is critical that consultants incorporate sleep and rest states into their evaluations, get a better knowledge of the need for proper sleep and all the factors that influence it (including nutrition) by doing academic research in mammals, and implement adapted strategies for counseling dog owners accordingly.


References

Abrantes, R. (2015). Dogs Home Alone. Wakan Tanka Publishers.


Adams, G., & Johnson, K. (1993, April). Sleep-wake cycles and other night-time behaviours of the domestic dog Canis familiaris. Applied Animal Behaviour Science36(2–3), 233–248. https://doi.org/10.1016/0168-1591(93)90013-f


Bódizs, R., Kis, A., Gácsi, M., & Topál, J. (2020). Sleep in the dog: comparative, behavioral and translational relevance. Current Opinion in Behavioral Sciences33, 25–33. https://doi.org/10.1016/j.cobeha.2019.12.006


Earth and Life Studies, D. O., Life Sciences, C. O., Radiation Effects Research, B. O., & Council, N. R. (1993). Perception and Behavioral Effects of Electromagnetic Fields. Assessment of the Possible Health Effects of Ground Wave Emergency Network. Washington (DC): National Academies Press (US). https://www.ncbi.nlm.nih.gov/books/NBK208988/


Giannetto, C., Fazio, F., Assenza, A., Alberghina, D., Panzera, M., & Piccione, G. (2014). Parallelism of circadian rhythmicity of salivary and serum cortisol concentration in normal dogs. Journal of Applied Biomedicine12(4), 229–233. https://doi.org/10.1016/j.jab.2014.01.009


Hart, V., Nováková, P., Malkemper, E. P., Begall, S., Hanzal, V., Ježek, M., Kušta, T., Němcová, V., Adámková, J., Benediktová, K., Červený, J., & Burda, H. (2013, December). Dogs are sensitive to small variations of the Earth’s magnetic field. Frontiers in Zoology10(1). https://doi.org/10.1186/1742-9994-10-80


Masters, A., Pandi-Perumal, S. R., Seixas, A., Girardin, J. L., & McFarlane, S. I. (2014). Melatonin, the Hormone of Darkness: From Sleep Promotion to Ebola Treatment. Brain disorders & therapy4(1), 1000151. https://doi.org/10.4172/2168-975X.1000151


Mondino, A., Catanzariti, M., Mateos, D. M., Khan, M., Ludwig, C., Kis, A., Gruen, M. E., & Olby, N. J. (2023). Sleep and cognition in aging dogs. A polysomnographic study. Frontiers. https://doi.org/10.3389/fvets.2023.1151266


Ohmori, K., Nishikawa, S., Oku, K., Oida, K., Amagai, Y., Kajiwara, N., Jung, K., Matsuda, A., Tanaka, A., & Matsuda, H. (2013). Circadian rhythms and the effect of glucocorticoids on expression of the clock gene period1 in canine peripheral blood mononuclear cells. The Veterinary Journal196(3), 402–407. https://doi.org/10.1016/j.tvjl.2012.10.010


Palazzolo, D. L., & Quadri, S. (1987). The effects of aging on the circadian rhythm of serum cortisol in the dog. Experimental Gerontology22(6), 379–387. https://doi.org/10.1016/0531-5565(87)90019-2


Reif, J. S., Lower, K. S., & Ogilvie, G. K. (1995, February 15). Residential Exposure to Magnetic Fields and Risk of Canine Lymphoma. American Journal of Epidemiology141(4), 352–359. https://doi.org/10.1093/aje/141.4.352


Schork, I. G., Manzo, I. A., De Oliveira, M. R. B., da Costa, F. V., Young, R. J., & de Azevedo, C. S. (2022). The cyclic interaction between daytime behavior and the sleep behavior of laboratory dogs. Scientific Reports12(1). https://doi.org/10.1038/s41598-021-04502-2


Tooley, C., & Heath, S. E. (2022, July 8). Sleep Characteristics in Dogs; Effect on Caregiver-Reported Problem Behaviours. Animals12(14), 1753. https://doi.org/10.3390/ani12141753