Bees get less sleep while caring for the young, study suggests

Caring for newborns is seemingly as tough for bees as it is for humans.

New research suggests worker bees tending to the young get less sleep compared to fellow insects – such as drones (male bees) and queen bees.

The team say their findings, published in the journal Current Biology, add to emerging evidence that animals are able to give up sleep if the need arises.

Worker bees are sterile females who make up the largest percentage of bees in a hive.

They begin their lives as nurse bees, caring for and cleaning up after the queen and feeding the larvae, before moving on to the role of caring for the entire colony.

Previous research has shown that worker bees adjust their sleep patterns depending on their role in the colony – with foragers showing strong sleep and wake cycles and nurse bees working around the clock to tend the brood.

The scientists studied brood-tending bumble bees and analysed their sleep behaviour by performing sleep disturbance experiments and looking at their response thresholds, ie their ability to perform tasks in various situations.

They found that the nurse bees not only sacrificed their shuteye to look after the larvae, their lack of sleep continued when the brood moved on to their pupal stage and did not need to be fed.

The researchers believe that certain chemicals produced by the pupae could be causing sleep deprivation in their carers.

However, when the pupae and their substances were removed the bees did not show a sleep rebound, suggesting they were not sleep deprived in the expected way, the researchers said.

Moshe Nagari, a postdoctoral fellow at Hebrew University and lead author, added: “The fact that the nursing bees sleep so little, even when caring for pupae that do not need to be fed, was the most surprising.

“Before this study, we assumed that the main functions of activity around the clock without circadian rhythms in nurse bees is to provide improved feeding to the developing larvae, enabling them to grow rapidly.”

The researchers say other animals – such as birds and fish – have shown the ability to give up sleep in certain circumstances.

For example, birds sleep less during their seasonal migrations while some cavefish have evolved to sleep less compared with their counterparts that live in open water habitats. Also, some male birds and fruit flies will sacrifice their sleep to give themselves more time to mate.

The team add that their findings open the door to further research on whether sleep deprivation affects health or cognitive performance.

Guy Bloch, a professor at Hebrew University and study co-author, said: “Our findings show that sleep is more plastic and less rigid than is commonly accepted.

“With bees, if there is no cost for sleep loss, it means that the brood-tending bees have a mechanism that allows them to significantly reduce sleep without a cost to their brain or other tissue.

“This, of courses, raises the question about what exactly are these mechanisms and what is the basic function of sleep.”