Q: How close is hibernating to real sleep? Do you have dreams? – Lesley Barnett, Ohio
A: I have been called a dreamer (when I was a younger bear), but perhaps you mean the kind of dreams that usually hit during REM sleep. I have those, too. (There’s this recurring one about an unattended dumpster outside of a Denny’s…)
Hibernation is a different beast. In fact, most hibernating animals shut off their neurobiology almost completely, and studies have shown that there’s almost no brain activity going on during the long winter’s nap—certainly not enough to dream.
However, bears don’t truly hibernate. Instead, we go into an extended ultra-slow metabolic state called “torpor.” During our winter torpor, we keep our bodies around 86°F rather than getting into the much lower ranges common in true hibernators, which can drop their internal temps as low as 39°F.
But here’s where it gets interesting. There hasn’t been a lot of research done on bear brains (we’re a little hard to get ahold of, and don’t much like electrodes), but there have been plenty of studies done on the dreaming abilities of rodents and primates. Research on hibernating lemurs has shown that the little guys go into a REM-like state when their body temperature drifts up to 86°F on warm days—and that’s our usual temperature range.
So, while scientists can’t say for sure, it seems possible that we do dream during hibernation. And, no I haven’t asked other bears about it—you try giving a survey to someone just waking up from a six-month nap.
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