Light signals control sleep, fruit fly study shows

Researchers at the University of Leicester have discovered that light sensed through the eyes plays a direct role in regulating sleep, at least in fruit flies - and the findings could shed light on human sleep disorders.

Sleep is governed by both the body’s circadian clock and its sleep homeostasis system, which tracks the need for rest. While light is known to influence circadian rhythms, how it affects sleep homeostasis has remained unclear.

In the study [1], published in ScienceDirect, the team genetically disabled key visual genes and neurons in Drosophila melanogaster, then monitored sleep using an infrared motion-sensing system. Flies with impaired vision showed fragmented daytime sleep and, in some cases, reduced total sleep.

Ko-Fan Chen, lecturer in Neurogenetics  in the University of Leicester’s School of Biological Sciences, and corresponding author, explained: “Our results show that visual input from the eyes actively promotes normal sleep patterns. Even in flies, light signals help stabilise rest - suggesting similar pathways could exist in humans.”

Lead author Yu-Chien Hung said: “The fruit fly can now serve as a rapid platform to explore genes that influence sleep, including those linked to vision disorders. This opens up opportunities to better understand sleep regulation and potentially develop targeted therapies.”

Mehram Akhtar added: “Our results suggest that proper daytime light exposure supports healthy sleep, while dim or poorly lit environments could disrupt natural sleep patterns.”

The work was supported by the University of Leicester’s £9 million Future 100 PhD programme, which funds innovative research across multiple disciplines.

More information online

1. A day sleep promoting role of phototransduction in Drosophila melanogaster published in ScienceDirect