Light exposure could hold the key to a good night’s sleep
From left: Ko-Fan Chen and Yu-Chien Hung
Light signals processed through the eyes helps regulate sleep in fruit flies, and disrupting those visual pathways causes abnormal sleep patterns, a new study shows.
The results pave the way for greater understanding of human sleep disorders and potential treatments.
Sleep is controlled by two main systems – the circadian clock (24-hour body rhythm) and sleep homeostasis (the body’s need for sleep). While light is a major environmental signal that influences both these systems, how light directly affects sleep homeostasis is less understood.
Scientists at the University of Leicester studied sleep in the fruit fly Drosophila melanogaster, a common model organism in sleep research. The results have just been published in ScienceDirect.
Researchers were able to turn off an array of genes and neurons required for vision in the fruit fly, disrupting its ability to see clearly.
Using an infrared motion sensing device - much like a burglar alarm motion detection system – the research team was able to check if the visually compromised flies were sleeping (immobile) or not sleeping (walking).
They also verified if the flies’ vision was compromised by measuring its neuronal eye function – the complex signal transmission that connects its retina to the brain.
Researchers found that flies with compromised vision had fragmented daytime sleep and sometimes reduced total daytime sleep.
Ko-Fan Chen, lecturer in Neurogenetics in the University of Leicester’s School of Biological Sciences, and corresponding author on the paper said: “We now know that visual input from the eyes helps regulate and promote normal sleep patterns and the same can be said for humans.
“Overall, the results suggest that visual input from the eyes helps regulate and promote normal sleep patterns. Our findings settle an important research question and could enable us to uncover the pathways for triggering sleep in the human brain.”
Yu-Chien Hung, lead author and Biotechnology and Biological Sciences Research Council-funded postdoctoral research associate added: “While the fly and human are distantly related, they share certain similarities – including the detection of light via the retina which sends signals to the brain’s sleep centres.
“We now know that these light and visual signals also promote sleep in the fly. This is exciting because by applying the same experimental design from this study, the fruit fly can now be used to rapidly identify novel gene functions in the future with the potential to investigate vision disorder-linked sleep problems in humans.”Mehran Akhtar
The research project was supported by the University’ of Leicester’s Future 100 PhD programme – a prestigious scholarship programme to fund 100 PhD opportunities over a 10-year period using £9 million investment.
Future 100 aims to nurture tomorrow’s research leaders, pushing new innovations across a wide range of disciplines, from AI and climate change to medicine, social sciences and space.
Fellow author and PhD Mehran Akhtar, added: “The results show that proper light exposure during the day may help stabilise sleep while poor light environment such as dim days or poor office lighting, could actually disrupt sleep patterns – making it harder for us to fall asleep or to stay asleep once we do.”