At the level of species: hibernating, winter sleeps with mad awakenings at springtime:
'The Alaskan fur seal bull is the best-known example of fasting by a mammal during the mating season. All through the summer he neither eats nor sleeps. It is just one long debauch of fighting and love-making and guarding his harem against unscrupulous invaders. As a result of all this activity, by September he is a wreck of his former self. All his fat has disappeared, for that is what he has been living on by absorption all summer. His bones protrude, his side is torn and scarred, he is weary unto death. Blessed sleep is what he needs. Forsaking his harem, he waddles back into the long grass far away from the beach, there to stretch out in the warm sun. He will sleep for three weeks on end without waking, if undisturbed'.
(Dr. H.M. Shelton, Le Jeûne: Une Technique millénaire, Laffont, 1978)