Artificial light disrupts honeybee sleep patterns

Sleep experts advise against screen time in bed, cautioning that light from phones and electronic devices can interfere with our natural sleep patterns. 

This is one example of how science is becoming more attuned to the wide-ranging health impacts linked to circadian rhythms and our daily sleep-wake cycles.

Artificial light and honeybees

Now, a team of researchers led by the University of California, San Diego (UC San Diego) has revealed that artificial light also disrupts the circadian rhythms of honeybees, posing a risk to their role as pollinators. 

“Our research shows just how sensitive honeybees are to changes in their environment, particularly to something as seemingly benign as artificial light,” said lead author Ashley Kim, a PhD student in biology at UC San Diego. 

“By disrupting their circadian rhythms, we see clear evidence of reduced sleep periods. This raises significant concerns, not only for bee health but also for the health of ecosystems that depend on them for pollination.”

Night light and sleep disturbances

Honeybees are key pollinators for many wild plants and agricultural crops, essential for both ecosystem stability and global food security. These bees typically prefer nesting in dark spaces, though a little light enters from the hive entrance. 

When bees are exposed to artificial light at night (ALAN), particularly in urban areas, their sleep is disturbed, and as temperatures rise, bees may be even more exposed to ALAN. 

The growing popularity of urban beekeeping to support bees and their pollination services means more honeybees may be facing these artificial light challenges.

Artificial light and honeybee behavior

Poor sleep from light exposure impairs bee behaviors crucial for hive health, including their complex communication system called the “waggle dance,” which helps bees share information about food sources. 

To study this impact, UC San Diego researchers conducted experiments over several years, comparing bees sleeping in darkness with bees exposed to constant light. The results showed that bees in constant light had disrupted sleep, as Kim observed through 24-hour video recordings.

“Even without analyzing the data, you can tell that there was something going on…the bees that were under constant light slept less,” she said. 

“The effects of light pollution on biological systems is fairly unknown and something people normally don’t think about, which is why it’s a rapidly evolving field.”

Growing threat of light pollution

“Understanding the factors that affect bee health, such as light pollution, is essential for developing strategies to protect pollinator populations,” said senior author James Nieh, a professor of biology at UC San Diego. 

As artificial light now covers over a quarter of the Earth’s surface, the study highlights the urgent need to understand how these disruptions may be harming bees and other pollinators. 

Continuous artificial light exposure caused honeybees to sleep less, and their hive-mates disturbed them more frequently compared to bees resting in the dark. In experimental cages, bees under constant light sought darker areas.

ENLACE initiative in pollinator research

This research also highlights UC San Diego’s ENLACE program, which connects students from Latin America and the U.S. to research global challenges like pollinator health. 

Students who participated in the ENLACE initiative, such as Aura Velazquez and Belen Saavedra, contributed as co-authors on the study. 

“This project exemplifies the impact of ENLACE, bringing diverse perspectives to address environmental challenges like pollinator health and environmental sustainability,” said Olivia Graeve, ENLACE director and UC San Diego professor.

Future research directions

UC San Diego’s Catalyst Fund recently awarded Nieh and study co-author Benjamin Smarr a grant to extend their research on circadian rhythms to broader environmental and human health issues. 

Their project, “Harmonizing the Pulse of Life: Pioneering Circadian Insights for Human and Ecosystem Health at UC San Diego,” will explore the effects of circadian disruptions from bees to entire ecosystems. 

“This program fosters interdisciplinary collaboration, bringing together experts in biology, data science, and medicine to address issues like light pollution and its impact on pollinator health,” said Nieh. 

The Catalyst Grant reinforces UC San Diego’s commitment to sustainability and human well-being, offering innovative ways to mitigate light pollution’s effects on pollinators and beyond.

The study is published in the journal Nature Scientific Reports. A preprint can be found on BioRxiv.

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