Recent findings from researchers at Ruhr-University Bochum, Ankara University at Prince Edward Island, and Bari Aldo Moro University reveal that two-thirds of domestic cats (Felis Catus) tend to sleep on their left side. This orientation provides them with a left field of vision, allowing the right hemisphere of their brain to have an unobstructed view of impending approach, while protecting their body.
Isparta et al. We propose that the significant left-side preference in cat sleep may have evolved alongside hemispheric asymmetry related to threat assessment. Image credits: Noah Dustin von Weissenfrue / Gleb Kuzmenko / Isparta et al., doi: 10.1016/j.cub.2025.04.043.
“Sleep represents one of the most vulnerable states for animals, particularly during deep sleep when vigilance to threats is notably diminished.”
“Domestic cats act as both predators and prey (to animals like coyotes), averaging 12-16 hours of sleep per day.”
“This implies they spend around 60-65% of their lives in highly susceptible states.”
“To minimize the risk of becoming prey, cats tend to rest in elevated locations, where they can better see approaching threats while remaining concealed.”
“In such elevated spots, predators can typically only approach from below.”
“Thus, resting at height affords cats a sense of safety, comfort, and a vantage point to observe their surroundings.”
The authors of this study examined 408 publicly available YouTube videos featuring individual cats lying on their sides in clear sleep positions, ensuring unbroken sleep durations of at least 10 seconds with full visibility from head to tail.
Only original, unedited videos were considered; those that were low resolution, obscured, duplicated, or altered (such as mirror images or selfies) were excluded.
The findings showed that 266 cats (65.1%) exhibited left-oriented sleep positions, while 142 demonstrated a significant left-sided bias as a population, compared to the 34.8% that slept on their right side.
“A cat that sleeps on its left side gains awareness of its environment upon waking with a left field of vision processed by the right hemisphere,” explained the researchers.
“This hemisphere is critical for spatial awareness, handling threats, and coordinating quick escape responses.”
“When a cat awakens after sleeping on its left side, visual cues regarding predators or prey are relayed directly to the right hemisphere of the brain.
“This suggests that favoring the left side while sleeping might be a strategic survival behavior.”
study published in the journal Current Biology.
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Sevim Isparta et al. 2025. Sleeping orientations of domestic cats on both sides. Current Biology 35 (12): R597-R598; doi: 10.1016/j.cub.2025.04.043
Source: www.sci.news
