Hibernating animals do not experience dreams, as scientists explain. This phenomenon raises intriguing questions about their brain activity during sleep.

The Earth's history spans over 4.5 billion years, during which our planet has become home to a vast number of species: some have long since gone extinct, while others continue to thrive. Most terrestrial species have been well studied; however, there are still some that continue to astonish scientists, as noted by Science Focus.

It is known that many species on Earth enter hibernation, typically to survive adverse environmental conditions. Among them are bears, bats, ground squirrels, badgers, jerboas, hedgehogs, lemurs, and many others. But do animals dream during this process? The short answer is: unfortunately, no.

Researchers point out that this is due to the fact that hibernation and sleep are not the same. Essentially, sleep represents a more physiologically "active" state. It is known that during sleep, our body and system recover from wakefulness, while the metabolic and electrical activity of the brain does not decrease.

Hibernation, on the other hand, requires the body to significantly reduce virtually all types of activity, including brain activity, to conserve energy. Previous studies have already shown that animals entering hibernation lower their breathing rate and decrease their body temperature to conserve as many resources as possible. Scientists have also found that during hibernation, the body's metabolic rate drops incredibly — results indicate that, on average, the metabolic rate during hibernation reaches only about 5% of the normal level.

Thus, scientists concluded that animals simply lack sufficient brain activity to be able to dream. However, there is an exception to the rule. Previously, researchers discovered one exception to this rule — the fat-tailed lemur.

It is known that fat-tailed lemurs are the only primates that enter hibernation. Researchers conducted a series of experiments and observed this species experiencing periods of rapid sleep during hibernation.

Earlier, scientists also studied various strategies used by animals for survival in particularly harsh conditions. They found that some animals can enter hibernation, while others fall into a state known as torpor.