In order to have more time for sex during the mating season, male broad-footed marsupial mice sometimes sacrifice several hours of sleep per night. This is the conclusion of an international study published in the journal “Current Biology”.
The movements and sleep of Swainson’s and gray broad-footed marsupial mice (Antechinus swainsonii and A. agilis), which only live in Australia, were measured. According to the researchers, it is the first study to provide direct evidence of this type of sleep restriction in a terrestrial mammal.
“Using a combination of techniques, we showed that males sleep less during the mating season,” said lead author Erika Zaid from La Trobe University in Melbourne, Australia. One male even reduced his sleep by half. “In humans and other animals, limiting the amount of normal sleep leads to poorer waking performance – an effect that increases night after night. And yet the broad-footed marsupial mice did exactly that: they slept three hours less per night, every night, three for weeks.” Sleep time remained unchanged in females.
Death after mating season
For the small marsupials, it is a trade-off between sleep and reproduction, which is probably due to strong sexual selection, as the study states: Male broad-footed marsupial mice experience only one mating season, after which they die. This rare reproductive strategy is also called semelparity.
During their first and only mating season, males compete to have contact with as many females as possible to maximize their chances of successful reproduction, according to the study authors.
“It’s actually a little surprising that the animals don’t sacrifice more sleep during the mating season since they’re going to die soon anyway,” Zaid said. “In this way, much of their sleep is preserved, which highlights the basic functions of sleep.”
According to the study, it remains unclear why the males die after the three-week mating period when they are only about one year old. The lack of sleep is probably not a decisive cause – animals with less sleep were not in worse condition than those with more sleep.
