 During the winter months, food for animals is sparse. Many species survive by conserving their energy through hibernation. During this process, an animal's body's temperature and heart rate drops, and their breathing rates are reduced by 50 to 100%. That is bonkers. Their bodies are too cold to produce electric currents related to dreaming, so they enter long periods of REM sleep. Dormais hold the record for the longest hibernators up to 11 months. 11 months! In fact, the name Dormouse comes from the French word dormir, meaning to sleep.