New research reveals that sleep patterns of zebrafish are similar to the slow-wave and REM sleep of humans and other mammals, birds, and lizards. Furthermore, the study suggests that these sleep signatures emerged in the brain of our common ancestor more than 450 million years ago. According to the scientists, a better understanding of how sleep evolved could shine light on the biological processes behind it and perhaps lead to new treatments for sleep disorders. From National Geographic:
Based on our understanding of the evolutionary relationships between fish and mammals, the team suggests that REM-like sleep states evolved more than 450 million years ago, making this type of sleep a deeply held biological phenomenon.
"We share a backbone, but we share much more than that," says study coauthor Philippe Mourrain, a neuroscientist at Stanford University. "It makes it easier to understand sleep and what it does in ourselves…"
Lead author Louis C. Leung, a neuroscientist at Stanford University, built the microscope responsible for the complex imaging done for the study. Most body activity is choreographed by an intricate network of nerve cells, or neurons. When neurons are active, they release calcium, so researchers genetically engineered the zebrafish to include a protein that would flash fluorescent green when it detected calcium, indicating an area of the body is active…
The advance could be particularly valuable for health professionals seeking to design new drugs to combat the growing epidemic of sleep deprivation in many countries. Better sleep-enhancing drugs could provide some relief for people who struggle to drift off. By implementing these techniques in the future, we can potentially better screen drugs to see if they activate the right cells, so that patients wake up feeling refreshed, Leung says.
"Neural signatures of sleep in zebrafish" (Nature)
image: "Female zebrafish" by Azul (Wikimedia Commons)