Endangered male northern quolls are giving up sleep for more sex - and it could be killing them, according to new research from Australia.
The study found that males travel long distances in search of mating partners, often giving up sleep in the process.
A lack of rest may explain why males of the carnivorous marsupials typically mate themselves to death in one breeding season, experts say.
Females, on the other hand, can live and reproduce for up to four years.
"They cover large distances to mate as often as possible and it seems that their drive is so strong that they forgo sleeping to spend more time searching for females," said Christofer Clemente, senior lecturer at the University of the Sunshine Coast. His institution led the study with the The University of Queensland. The research was published on Wednesday.
Researchers collected data over 42 days after fitting backpacks with trackers on wild roaming male and female northern quolls on Groote Eylandt, an island off the coast of Australia's Northern Territory.
Some quolls they studied walked more than 10km in one night, which translates to nearly 40km in human distance, based on average stride length, the study said.
Males of the species also appeared to attract more parasites. The most likely reason: they devote less time to grooming so they can make the most of each breeding season. Researchers said the males are not as vigilant as females while searching for food or avoiding predators.
"Sleep deprivation, and associated symptoms for a prolonged duration would make recuperation impossible and could explain the causes of death recorded in the males after breeding season," said Joshua Gaschk, the study's lead author. "They become easy prey, are unable to avoid vehicle collisions, or simply die from exhaustion."
Mr Gaschk added that the initial data points to the need for further studies on how sleep deprivation affects quolls and wider families of marsupial mammals found in Australia and Papua New Guinea.
"If male quolls forgo sleep to the detriment of their survival, northern quolls [will become] an excellent model species for the effects of sleep deprivation on body function," he said.
According to the Australian Wildlife Conservancy, there are some 100,000 northern quolls remaining but the population has been "undergoing rapid decline". Loss of habitat due to development and attacks by stray cats pose a serious threat, and they are also particularly vulnerable to being poisoned by cane toads.