New research released by WA's Department of Biodiversity, Conservation and Attractions (DBCA) has found northern quolls will regularly take naps about midnight.

Department researcher Harry Moore said the discovery had changed previously held perceptions of northern quolls.

"We've always assumed that northern quolls are nocturnal," Dr Moore said.

"Something we noticed in our recent work was that we were seeing quolls actually dropping off in activity around midnight."

Dr More described the quolls as having a regular pattern of rest and activity, every night.

"They'd be active in the early part of the night, they'd have a rest, and then they'd be back up and going, just before dawn," he said.

The department's discovery was made while studying quolls across the Pilbara region.

The northern quoll is native to areas in the Kimberley, the Northern Territory and on Queensland's far north-eastern coast.

Dr Moore said the team was surprised to learn the trend persisted across all northern quoll populations.

Unsure why:

Having noticed the trend of midnight naps, researchers said they were puzzled by the findings.

Several theories have been proposed, including quolls adapting to lunar phases, and avoiding the time of night when the moon was at its brightest.

But Dr Moore thought it could be something to do with how quolls digested their food.

"Like a lot of us, sometimes after you have a big meal, it's good to lie down and do a bit of digestion," he said.

"They have a bit of a siesta, as they say in Spain."

But he said researchers were not 100% sure why quolls loved a nap.

Dr Moore said the team was keen to keep tracking and studying the small and elusive marsupial.

Dr Moore said tracking collars were used with photographic evidence to give researchers an insight into when quolls were active.

Recent research conducted with the same tracking collars uncovered how quolls living near mine sites needed to expel more energy to find food. 

Dr Moore said the next step would likely be to study northern quolls in captivity, as current methods were not suited to solving the mystery.

But Dr Moore said for now, the mystery of the midnight siesta remained.

Original Story By | By Kelly Gudgeon and Charlie Mills