Biologists from the California Institute of Technology, US, have conducted a promising research that could improve our understanding of the process of sleep-wake regulation. The researchers have identified a gene that when over activated causes severe insomnia.
This gene is neuromedin U (Nmu), a neuropeptide found in the brain of mammals, birds, fish and insects. Nmu seems to behave as a natural stimulant. In the study, the fish that lack this gene need more time to become fully awake and are less active during the day.
The results of this study may help to better understand the mechanisms of sleep, a process we know very little about despite its undoubted importance. In the long term, the results suggest that the Nmu gene could be a candidate for new therapies to treat sleep disorders.
This study appears in the February 17, 2016 issue of the journal Neuron.
The mysterious process of sleep
David Prober, Assistant Professor of Biology at Caltech and one of the research participants, noted that “sleep is a mysterious process. We spend a third of our lives doing it, and every animal with a complex nervous system seems to do it, so it must be important. But we still do not understand why we do it or how it’s regulated.”
Zebrafish: the protagonist of the study
For the study, the researchers chose zebrafish. Recently, zebrafish have become a valuable vertebrate model for studying sleep. Working with zebrafish is easier than working with other animals traditionally used in research such as mice. Many fish can be raised in a small space, they develop rapidly, exhibit complex behaviors when they are just five days old and they are transparent during the embryonic and larval stages so it’s easier to track what is happening inside their brains.
Like humans, zebrafish need to sleep at night. In this regard, Prober states that zebrafish and mammals brains may share the basic neural circuits that regulate sleep.
Is there a gene of insomnia?
During the study, researchers found that zebrafish started to wake up at the end of the night and became more active when the light came on. They identified the genes involved in this mechanism and developed transgenic fish for each of these genes. Finally the most significant change was the result of overexpression of Nmu, a gene which is also found in mammals.
Fish that showed an overexpression of Nmu were much more active both during the day and night, pointed Prober.
However, genetically modified fish that lacked that gene had troubles waking up in the morning and were less active during the day. “So it seems that this gene is particularly important for the transition from nighttime sleep to daytime wakefulness.” Prober said.
A promising way forward
However, ‘the gene of insomnia’ does not cause sleep disorder itself, but the impaired functioning. When the function of this gene was interrupted, fish did not sleep the first night. The following nights fish had trouble sleeping and waking, and finally they reached a state of human-like insomnia.
Prober said that several genes involved in sleeping and waking have been identified. However, scientists still do not know which are the relevant ones that cause sleep disorders in humans. “Our study suggests that Nmu could be a good gene to look into.”
In the long term, the findings of this study may pave the way for the development of therapies for sleep disorders and solve this problem that affects millions of people.