Don’t Wake Me, I Plan On Sleeping In

Behold the wreckage
of night, one heck
of a mess: covers…
cast off in vast
deserts of insomnia
where trepidations bomb
tranquility to rubble. ~Stephen Cushman

The cure for insomnia? Get plenty of sleep. ~W.C. Fields

Potentially good news in the realm of sleep studies, dear galleons, particularly if you (like me) suffer from chronic insomnia:

Scientists have located a “sleep switch” in fruit flies.

A group at Washington University School of Medicine in St. Louis discovered a group of a mere 20 cells in the brains of fruit flies that control when and how long the flies sleep. These 20 cells were found in a part of the fly brain known as the dorsal fan-shaped body:

Paul Shaw, associate professor of neurobiology, led the group as they genetically modified these cells, increasing their activity. This modification led to the flies sleeping an additional seven hours a day. Tweaking this, the group added a gene that made the cells active only at certain temperatures- allowing them to control when/how long the flies slept just by adjusting the temperature in the flies’ environment.

“This is exciting because this induced sleep state so far appears to be very similar to spontaneous sleep,” said Shaw. “That means we can manipulate these cells to explore a whole new realm of questions about the purposes of sleep. Such studies might one day lead us to more natural ways of inducing sleep in humans.”

More on this in a minute.

I suppose you are all wondering the same thing…

Why fruit flies?

Well, a few years ago, a group out of the University of Missouri-Kansas City found that the circadian rhythms of fruit flies are regulated by similar cellular machinery to that of humans. As such, they have become some of the most viable animals models for sleep research.

Strange but true.

Now, while some of the machinery of sleep have strong correlates between flies and humans, fly brains and human brains have very different overall structures. We have yet to find a human counterpart to the dorsal fan-shaped body, but Shaw’s team is looking  to match human brain cell types to the fly brain cells they singled out based on the chemical messengers the cells produce.

So, fellow insomniacs, while this isn’t a quick-fix cure, if Shaw’s group can locate a similar set of cells in the human brain, we might finally have a solution to our sleep problems.

Wouldn’t that be nice?

***

There’s actually more to Shaw’s research than just hope for insomniacs. An even more interesting bit of information to come out of this study revolves around sleep and memory.

For many years, scientists have believed there is a deep connection between sleep and long-term memory formation. Students are frequently made aware of studies that have found studying and then sleeping the night before an exam proves more beneficial than pulling an all-nighter to cram. This has been attributed to the help sleep seems to give to memory formation- by “sleeping on the information,” the brain is actually able to synthesize and store more of it.

Except… while there have been plenty of studies hinting at and dancing around the idea of sleep contributing to memory formation, there’s been surprisingly little real proof of it (there was a pretty solid study in 2009 out of MIT using mice, but if there’s one thing we know about science it’s that a single study does not a theory prove).

Which is why the second part of this study is so important- it directly proves this link.

The reason the memory portion of the study cropped up was as a test of whether the induced sleep was the same as spontaneous sleep. If the induced sleep also proved essential to the formation of long-term memories, the two types of sleep could be considered the same.

To do this, male flies were exposed to other males genetically modified to make female sex pheromones in a process known as ‘courtship conditioning.’

“The subject fly will initiate courtship because of the female pheromones, but the modified male making those pheromones inevitably rejects him,” said Jeff Donlea, a postdoctoral research assistant at Oxford University.

Our researchers used a training protocol that creates a memory that normally only lasts a few hours in flies- after being rejected multiple times by the modified males, the fly learns not to make advances when he approaches the modified males at a later time. Again, this memory normally only lasts a few hours. However, when researchers used that ‘sleep switch’ to induce sleep in the flies, the fly managed to form a long-term memory of the experience which lasted for several days.

Worried that this could be attributed to the fact that they had overly excited those cells, our group activated those sleep cells after training but prevented the flies from actually sleeping. The long-term memories were not formed, proving that it was the sleep that proved essential to memory formation.

Simple though it may seem, it’s one of the few times we’ve made this kind of direct, verifiable connection between sleep and memory formation.

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