Skeptophilia (skep-to-fil-i-a) (n.) - the love of logical thought, skepticism, and thinking critically. Being an exploration of the applications of skeptical thinking to the world at large, with periodic excursions into linguistics, music, politics, cryptozoology, and why people keep seeing the face of Jesus on grilled cheese sandwiches.

Monday, August 8, 2016

Enter the Sandman

I've been fascinated with sleep ever since I can remember, and that's mostly because I've been a terrible sleeper ever since I can remember.  I'm one of those people who drifts off thirty seconds after my head hits the pillow, then wakes up at two AM with my mind spinning and can't get back to sleep for three hours.  All well and good on summer break, when I can take an afternoon nap if I need to, but it plays hell with my alertness and general mood during the school year.

Things have gotten a little better since I got a CPAP machine last year -- turns out I have obstructive sleep apnea due to a "narrow tracheal opening" (I have none of the other risk factors).  It was serious, too.  When I got the results of my sleep study, I was told that I was waking up an average of 23 times an hour.  Yes, that means that in an average eight-hour night, I was waking up over 180 times.

No wonder I was perpetually exhausted.

Since getting on a machine to regulate my breathing, it's gotten better, but I still am prone to wee-hours wakefulness and being tired in the middle of the day.  Annoying, but a malady I share with a lot of people, apparently.  And I've always wondered, what's sleep for, anyway?  What can possibly be so important that we slumber away on the order of a third of our life?

[image courtesy of photographer Evgeniy Isaev and the Wikimedia Commons]

The answer is: we don't know.  Evidently it's something not unique to humans -- virtually every animal species studied sleeps, and the more complex the brain, the more sleep they need.  There are hypotheses that sleep helps to reset the sensitivity of neurotransmitter receptors, that it allows consolidation of memories, that it facilitates the removal of toxic waste products from brain cells.  All are, at the moment, unproven.

All that's known is that when people are deprived of sleep for long enough, they kind of go off their rockers.

So it was with great interest that I read a paper last week in Nature called "Operation of a Homeostatic Sleep Switch" by Gero Miesenböck of Oxford University et al.  The research team studied sleep mechanisms in fruit flies:
Sleep disconnects animals from the external world, at considerablerisks and costs that must be offset by a vital benefit.  Insight into this mysterious benefit will come from understanding sleep homeostasis: to monitor sleep need, an internal bookkeeper must track physiological changes that are linked to the core function of sleep.
Miesenböck was interviewed by Sarah Kaplan of The Washington Post and described how an experiment on fruit flies could elucidate mechanisms of sleep in other animals:
Think about it.  We do it.  Every animal with a brain does it.  But obviously it has considerable risks...  If evolution had managed to invent an animal that doesn’t need to sleep... the selective advantage for it would be immense.  The fact that no such animal exists indicates that sleep is really vital, but we don't know why.
In order to study this response, Miesenböck's team used fruit flies that were genetically engineered for specific proteins to be switched on and off by laser light.  In particular, these flies had an artificial switch in their dorsal fan-shaped body (dFB), a cluster of cells that is known to be correlated with sleep.

They used the laser switch to release dopamine into the dFB, which suppresses activity in those cells, causing sleeping flies to immediately wake up.

In particular, there was one gated-channel protein that was off when the flies were sleeping and on when the flies were awake.  If the scientists turn the channel off permanently...

... the flies go into an unending sleep state.

It's like the stuff of fairy tales, except that there's no Prince Charming of the Fruit Flies.

The channel has been nicknamed "Sandman," for obvious reasons.  "It's beautiful, the self-correcting logic of the feedback mechanism," Miesenböck said.  "It's one of those things that gives you goose bumps when you see how it actually works because it's so, so unexpectedly simple and elegant."

An open question is whether the flies that can't wake up will live longer, since sleeping less is correlated with a shortened life span (both in fruit flies and in humans).  Miesenböck wasn't too fond of the idea of lengthened lifespan at the cost of never being awake, however.  "I don’t know if I would like to live longer if I am asleep most of the time," he said.  "I don’t know what the difference would be from being dead.  Anyway, it's getting philosophical now."

This research, however intriguing, is only the first step.  Whether humans have an analogous system is unknown -- as brain complexity increases, you might expect that the control systems would increase in complexity as well, but that's only a guess.  A complex switching system would likely engender more ways that it can fail.

After all, we don't see many insomniac fruit flies.

On the other hand, I'd love one of those laser-operated reversible sleep switches.  Switch on sleep at 10 PM, and have the "on" switch hooked up to my alarm clock.  Certainly preferable to tossing and turning for hours, although I do have to wonder what I'd do if the power went out in the middle of the night.

Oversleep, is my guess.
this mysterious benefit will come from understanding sleep
homeostasis: to monitor sleep need, an internal bookkeeper must
track physiological changes that are linked to the core function
of sleep
1
risks and costs that must be offset by a vital benefit. Insight into
this mysterious benefit will come from understanding sleep
homeostasis: to monitor sleep need, an internal bookkeeper must
track physiological changes that are linked to the core function
of sleep
1
Sleep disconnects animals from the external world, at considerable
risks and costs that must be offset by a vital benefit. Insight into
this mysterious benefit will come from understanding sleep
homeostasis: to monitor sleep need, an internal bookkeeper must
track physiological changes that are linked to the core function
of sleep
1

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