{"id":395633,"date":"2023-12-22T11:11:39","date_gmt":"2023-12-22T16:11:39","guid":{"rendered":"https:\/\/platohealth.ai\/reindeer-sleep-while-chewing-their-cud\/"},"modified":"2023-12-24T17:15:39","modified_gmt":"2023-12-24T22:15:39","slug":"reindeer-sleep-while-chewing-their-cud","status":"publish","type":"post","link":"https:\/\/platohealth.ai\/reindeer-sleep-while-chewing-their-cud\/","title":{"rendered":"Reindeer sleep while chewing their cud","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"
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Researchers report December 22 in the journal Current Biology <\/em>that the more time reindeer spend ruminating, the less time they spend in non-rapid eye movement (non-REM) sleep. EEG recordings revealed that reindeer\u2019s brainwaves during rumination resemble the brain waves present during non-REM sleep, and these brainwave patterns suggest that the reindeer are more \u201crested\u201d after ruminating. The researchers speculate that this multitasking might help reindeer get enough sleep during the summer months, when food is abundant and reindeer feed almost 24\/7 in preparation for the long and food-sparse arctic winter.<\/p>\n

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Researchers report December 22 in the journal Current Biology <\/em>that the more time reindeer spend ruminating, the less time they spend in non-rapid eye movement (non-REM) sleep. EEG recordings revealed that reindeer\u2019s brainwaves during rumination resemble the brain waves present during non-REM sleep, and these brainwave patterns suggest that the reindeer are more \u201crested\u201d after ruminating. The researchers speculate that this multitasking might help reindeer get enough sleep during the summer months, when food is abundant and reindeer feed almost 24\/7 in preparation for the long and food-sparse arctic winter.<\/p>\n

\u201cThe more reindeer ruminate, the less additional non-REM sleep they need,\u201d says first author and neuroscientist Melanie Furrer of the University of Zurich. \u201cWe think it\u2019s very important that they are able to save time and cover their sleep and digestive needs at the same time, especially during the summer months.\u201d<\/p>\n

Light-dark cycles are absent in the Arctic during winter and summer, and previous studies showed that Arctic-dwelling reindeer don\u2019t display circadian behavioral rhythms during these seasons, though they tend to be more active during the daytime during the spring and autumn equinox, when light-dark cycles are present. However, it was unknown whether these seasonal differences also impacted how much\u2014and how well\u2014reindeer sleep.<\/p>\n

To investigate the influence of seasonal light-dark cycles on reindeer sleep patterns, the researchers performed non-invasive electroencephalography (EEG) on Eurasian tundra reindeer (Rangifer tarandus tarandus<\/em>) in Troms\u00f8, Norway (69\u00b0N), during the autumn equinox, summer solstice, and winter solstice. The reindeer, who were all adult females, were part of a captive herd at UiT The Arctic University of Norway in Troms\u00f8, and the experiments were conducted in indoor stables with controlled lighting, unlimited food, and constant temperature.<\/p>\n

They found that reindeer slept approximately the same amount during winter, summer, and autumn, despite the fact that they were much more active during the summer. This is in contrast to other species who change the amount they sleep in response to environmental conditions. On average, the reindeer spent 5.4 hours in non-REM sleep, 0.9 hours in REM sleep, and 2.9 hours ruminating during a given 24-hour period, regardless of season. <\/p>\n

\u201cThe fact that reindeer sleep the same amount during winter and summer implies that they must have other strategies to cope with limited sleep time during the arctic summer,\u201d says Furrer.<\/p>\n

One possible strategy is the opportunity for rest during rumination\u2014the re-chewing of partially digested food, which is an important component of digestion for reindeer and other ruminants. Domestic sheep, goats, cattle, and Lesser mouse-deer have all been previously observed to produce sleep-like brain waves during rumination, but it was unclear whether rumination could serve a similar restorative function to sleep.<\/p>\n

The researchers found that the reindeer\u2019s EEG readings during rumination resembled brainwave patterns that are indicative of non-REM sleep including increased slow-wave activity and sleep spindles. Sleeping and ruminating reindeer also displayed similar behavior, tending to quietly sit or stand during both activities, and were less reactive to disturbances such as a neighboring reindeer sitting down or getting up\u2014reindeer directly responded to these disturbances (by looking toward the neighboring reindeer) 45% of the time if they were awake, but only 25% of the time if they were ruminating, and 5% of the time if they were in non-REM sleep.<\/p>\n

Next, the researchers tested whether rumination could reduce the reindeer\u2019s drive to sleep by depriving the reindeer of sleep for 2 hours and measuring their brain waves during sleep before and after this deprivation. Following sleep deprivation, the reindeer\u2019s EEG readings showed increased slow-wave activity, which is indicative of a build-up of \u201csleep pressure\u201d\u2014the unconscious biological drive for more and deeper sleep\u2014suggesting that reindeer experience deeper sleep following sleep deprivation.<\/p>\n

However, when the reindeer ruminated, this slow-wave activity was decreased during subsequent sleep, and the more they ruminated, the more the slow-wave activity decreased. \u201cThis suggests that rumination reduces sleep pressure, which could benefit the reindeer because it means they don\u2019t have to compromise on sleep recovery when they spend more time ruminating,\u201d says Furrer.<\/p>\n

This is especially important during the summer, because the more they eat, the more time the reindeer need to spend ruminating. \u201cRumination increases nutrient absorption, so it\u2019s crucial for reindeer to spend enough time ruminating during the summer in order to gain weight in anticipation of winter,\u201d says Furrer.<\/p>\n

Since reindeer appear to sleep while ruminating only some of the time, follow-up studies should compare the impact of rumination while sleeping with rumination while awake and would also ideally measure reindeer behavior and sleep in more natural outdoor conditions, the researchers say. However, such measurements would require surgically implanted EEG sensors rather than the non-invasive surface electrodes used in this study.<\/p>\n

 \u201cAnother thing we could add is to look at young reindeer,\u201d says Furrer. \u201cWe know sleep need is much higher in young children and babies compared to adults, so it would be interesting to look at sleep in younger reindeer.\u201d<\/p>\n

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This research was supported by the Swiss National Science Foundation and UiT The Arctic University of Norway.<\/p>\n

Current Biology<\/em>, Furrer et al., \u201cRumination can substitute for sleep in reindeer\u201d https:\/\/www.cell.com\/current-biology\/fulltext\/S0960-9822(23)01667-6<\/p>\n

Current Biology<\/em> (@CurrentBiology<\/a>), published by Cell Press, is a bimonthly journal that features papers across all areas of biology. Current Biology<\/em> strives to foster communication across fields of biology, both by publishing important findings of general interest and through highly accessible front matter for non-specialists. Visit http:\/\/www.cell.com\/current-biology. To receive Cell Press media alerts, contact [email protected]<\/a>.<\/p>\n

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Journal<\/h4>\n

Current Biology<\/p>\n<\/p><\/div>\n

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DOI<\/h4>\n

10.1016\/j.cub.2023.12.012 <\/i><\/p>\n<\/p><\/div>\n

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Method of Research<\/h4>\n

Experimental study<\/p>\n<\/p><\/div>\n

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Subject of Research<\/h4>\n

Animals<\/p>\n<\/p><\/div>\n

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Article Title<\/h4>\n

Reindeer in the Arctic reduce sleep need during rumination<\/p>\n<\/p><\/div>\n

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Article Publication Date<\/h4>\n

22-Dec-2023<\/p>\n<\/p><\/div>\n<\/div>\n<\/div>\n<\/div>\n