Wild Faces of Switzerland - Season 1 Episode 4 -

Marmots work hard all summer to feed incessantly and lay down enough fat reserves to pass the cold season in hibernation. But this is not to be confused with a refreshing night’s sleep: far from it. This is more like a life-threatening emergency state. Scientists have found out that marmots repeatedly need to come round from their hibernation and have a proper sleep if they are to survive the hostile winter at all.