Nearly all animals studied need to sleep, but little is known about why some animals sleep most of the day, while others sleep very little. As a result of living in total and permanent darkness in a small location in northeast Mexico, the eyeless, tiny blind Mexican cavefish (Astyanax mexicanus) has evolved sleeplessness, snoozing far less than their river-dwelling relatives. These fish have been studied for nearly 100 years for their fascinating traits, yet little is known about how their behavior evolves. Because of their lack of sleep, they provide a great model to study human sleep disorders such as insomnia.
A new study published in eLife by neuroscientists in the Charles E. Schmidt College of Science at Florida Atlantic University is providing new insight into the evolution of sleep.
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Image of Mexican cavefish and surface fish counterparts (top). Brains of surface fish (left) and cavefish (right) with wake-promoting Hypocretin protein depicted in green (bottom). Image Credit: Alex Keene, Florida Atlantic University