A little life, rounded with a sleep

An unsolved mystery of biology is the question of why we -- and just about every other animal studied -- have to sleep.

I've looked at this issue before here at Skeptophilia, and from the research I've read, we're no closer to a definitive answer.  There's the physical rest aspect, of course, but I think we can all attest that when you're exhausted, you don't recover equally well by sitting quietly awake for two hours or by taking a two-hour nap.  (In fact, if you're like me, when you're exhausted, sitting quietly for two hours without falling asleep is damn near impossible.)  There's some indication that sleep, especially the REM (rapid eye movement) stage wherein we dream, is critical for memory consolidation.  Other studies have found that during sleep, potentially toxic metabolic byproducts are cleared from the brain and cerebrospinal fluid, so sleep may act as a time for cleaning house.

Or all three.  And probably others.  But even if these are partial answers to the conundrum of sleep, they leave a number of facets of the sleep cycle unaccounted for.  Why, for example, does sleep need vary so greatly?  Elephants in the wild sleep about two hours a day; lions, on the other end of the spectrum, snooze for eighteen to twenty hours a day.  Famously, dolphins and whales do something even stranger.  They let half of their brain sleep at a time -- one side becomes quiescent, then that side wakes up and the other one takes a nap.

[Image licensed under the Creative Commons Jamain, Sleeping man J1, CC BY-SA 3.0]

Recent studies have shown that however far you go down the animal-brainpower-scale, they still sleep.  Insects and other arthropods sleep.  Even roundworms do.  One difficulty is that at that stage, it's a little hard to define what sleep is; certainly, the mental activity isn't going to be closely analogous to what goes on in a human's brain during the sleep cycle.  So most biologists use a functional definition: sleep is occurring if (1) the animal becomes quiet and hard to rouse, (2) the behavior is on some kind of a circadian rhythm, and (3) if you disturb the animal's sleep one day, they make up for it by sleeping longer the next day (something called sleep homeostasis).  These are sufficient to differentiate it from other behaviors that might mimic some aspects of true sleep -- hibernation, coma, anesthetization, inebriation, fainting, and so on.

This generates a fascinating result when you look at some of the simplest animals in the world; because a recent paper in the journal Science Advances has demonstrated that by this definition, hydras sleep.

Hydras are a group of freshwater animals in the Phylum Cnidaria, and thus are related to jellyfish, sea anemones, and corals.  This generates a difficulty if you try to apply any brain-based evolutionary reason for the ubiquity of sleep, because hydras don't have a brain.  They have a decentralized nerve net with no central nervous system whatsoever.  And yet, they undergo behavior that meet all three of the criteria of the functional definition for sleep.

This not only raises some interesting questions about the purpose of sleep, it brings up an entirely different one for the evolutionary biologists.  When did sleep evolve?  There's a general rule that the more ubiquitous a feature is (be it an organ, a protein, a gene, a behavior, whatever), the older it is evolutionarily and the more important it is to survival.  By this argument, sleep is really critical (which we already sort of knew), and it's really old.  Hydras are almost as distant as you can get from mammals on the family tree of Kingdom Animalia; our last common ancestor with hydras lived at least five hundred million years ago.  Amongst animals, only sponges are more distantly related.  It is possible that sleep is not a conserved feature -- that it was evolved independently on more than one of the branches of the family tree -- but in my mind, given the fact that every animal studied shows sleep behavior, it seems like it requires a great many more ad hoc assumptions to claim that sleep evolved over and over than it does to assert that we all inherited it from a common ancestor a very long time ago.

Nota bene: you might be thinking that the same could be said for the presence of eyes, but eyes almost certainly evolved separately in different groups.  We can tell this because however functionally similar the eyes of (for example) humans, flies, flatworms, and squids are, they are structurally different.  It may be that they all come from a common ancestor with light-sensing patches of some sort, but if so, in the interim each branch of Kingdom Animalia refined those structures in entirely different ways.  The same, by the way, is true of wings and the presence of flight in a number of different animal groups.

So the discovery that hydras sleep makes a curious question even curiouser.  Clearly, if sleep aids higher brain functioning and memory consolidation in humans, those were advantages it gained us much later, because as I mentioned, hydras don't even have brains.  The presence of sleep behavior in hydras and other simple animals points to it having a function in maintaining metabolism, so perhaps the "sleep as time to clean house" answer will turn out to be closer to the universal answer.

And who knows?  Maybe the next thing they'll find out is that sponges sleep, or that amoebas sleep.  At that point, we'll have a whole new set of questions, because those are organisms that not only lack a brain, but don't have nerves at all.  But given the ubiquity of snoozing in the animal kingdom, I actually wouldn't be surprised if it were true.

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Too many people think of chemistry as being arcane and difficult formulas and laws and symbols, and lose sight of the amazing reality it describes.  My younger son, who is the master glassblower for the chemistry department at the University of Houston, was telling me about what he's learned about the chemistry of glass -- why it it's transparent, why different formulations have different properties, what causes glass to have the colors it does, or no color at all -- and I was astonished at not only the complexity, but how incredibly cool it is.

The world is filled with such coolness, and it's kind of sad how little we usually notice it.  Colors and shapes and patterns abound, and while some of them are still mysterious, there are others that can be explained in terms of the behavior of the constituent atoms and molecules.  This is the topic of the phenomenal new book The Beauty of Chemistry: Art, Wonder, and Science by Philip Ball and photographers Wenting Zhu and Yan Liang, which looks at the chemistry of the familiar, and illustrates the science with photographs of astonishing beauty.

Whether you're an aficionado of science or simply someone who is curious about the world around you, The Beauty of Chemistry is a book you will find fascinating.  You'll learn a bit about the chemistry of everything from snowflakes to champagne -- and be entranced by the sheer beauty of the ordinary.

[Note: if you purchase this book from the image/link below, part of the proceeds goes to support Skeptophilia!]

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

Sleepless in upstate New York

Any regular reader of Skeptophilia who pays attention to the timestamp on my posts knows that I'm a bit of an insomniac.

I have suffered from chronic insomnia since I was a teenager.  It started with bizarre, vivid dreams, which often would wake me up (sometimes because I'd thrashed around so much I'd fallen out of bed).  Once awakened in the wee hours, it takes me long enough to fall back to sleep that I frequently just give up and get up.  Most of the conventional sleep aids haven't helped; the mild ones (like valerian and melatonin) are ineffective, and the stronger ones worry me because of their capacity to become addictive.  So mostly, I've just put up with it, living and working on a chronic sleep deficit, and trying to catch time to take catnaps whenever I can.

So, naturally, I was pretty intrigued when I ran across an article called "Life Without Sleep," by Jessa Gamble.  Her piece begins with a bit of a history of sleep deprivation, and includes the efforts by the military to come up with a way to combat fatigue in soldiers (most of which, by the way, were either ineffective in the long term or had dreadful side effects).  But my attention really perked up when she started talking about two potential therapies for chronic insomnia -- transcranial direct-current stimulation (TCDS) and transcranial magnetic stimulation (TMS) -- which work not by getting you to sleep, but by reducing the amount of sleep you need.

TCDS and TMS both work on the same principle; using an external energy source to trigger neuronal firing in the brain.  Both of these treatment modalities are, pretty much, what they sound like.  TCDS involves placing electrodes on the scalp, and introducing a electric current into the brain; TMS places the head in a powerful magnetic field.  Both of them have been used, with results that I'd file in the "interesting" column, to treat depression, anxiety disorders, and schizophrenia.  Both have no known long-term side effects, although TMS apparently has a low risk of causing seizure or fainting.  (For me, the main risk of TCDS is that I would spend the entire time worrying that I was participating in a reenactment of the climax of One Flew Over the Cuckoo's Nest.)

According to Gamble, both of these treatments show great promise in helping with insomnia.  About TCDS, she says:

After a half-hour session of the real treatment, subjects are energised, focused and keenly awake. They learn visual search skills at double the speed, and their subsequent sleep — as long as it does not fall directly after the stimulation session — is more consolidated, with briefer waking periods and longer deep-sleep sessions.

TMS apparently has shown similar results:

Using a slightly different technique — transcranial magnetic stimulation (TMS), which directly causes neurons to fire — neuroscientists at Duke University have been able to induce slow-wave oscillations, the once-per-second ripples of brain activity that we see in deep sleep. Targeting a central region at the top of the scalp, slow-frequency pulses reach the neural area where slow-wave sleep is generated, after which it propagates to the rest of the brain...  TMS devices might be able to launch us straight into deep sleep at the flip of a switch. Full control of our sleep cycles could maximise time spent in slow-wave sleep and REM, ensuring full physical and mental benefits while cutting sleep time in half. Your four hours of sleep could feel like someone else’s eight. Imagine being able to read an extra book every week — the time adds up quickly.

What I'm imagining, at the moment, is not feeling chronically exhausted, and not having to worry about falling asleep at the wheel during my ten-minute drive home from work (a fear I deal with on more days than I'd like to admit).  I imagine not constantly wondering when I'm going to have time to take a nap so I can actually be wide awake after eight o'clock at night.

It's a happy picture.

Of course, the worrywart side of me wonders what the long-term effects of this might be.  We still understand very little about why animals need sleep, and less still about why they dream.  Messing about with a physiological system we don't fully comprehend seems rather foolhardy.  On the other hand, the tests that have been done so far support the contention that TCDS and TMS are relatively safe, are non-invasive, and show great promise in dealing with chronic insomnia, a condition which according to the National Sleep Foundation plagues 10-15% of adults.

I'd volunteer to give it a try, even given the iffy status of the risks.

But right now, I think I'd better wrap this up, because the coffee's done brewing, and given how little sleep I got last night,  I could sure use a cup or two.  Or five.

Dream weavers

All my life, I've been plagued with vivid dreams.  I use the word "plagued" deliberately, because more often than not my dreams are disturbing, chaotic, and odd, leaving me unsettled upon waking.  I remember more than once thrashing about so violently during a dream that I've found myself in the morning on the floor in a heap of blankets; I've also had the residuum of unease from a bad dream stay with me through much of the following day.  And given that I've also spent most of my adult life fighting chronic insomnia, it's a wonder I get any sleep at all.

Of course, I've also had good dreams.  A series of flying dreams I had as a child were so realistic, and so cool, that for a while I was convinced that they were true; that I could go into my parents' front yard, angle my body to the wind, and be caught up and thrown into the air like a kite.  I've had dreams of running effortlessly, dreams of winning the lottery, and the inevitable (but admittedly pleasant) dreams of the non-PG-13-rated variety.

Through it all, though, I've never had a lucid dream.  Lucid dreams are dreams in which you are aware you're dreaming -- and apparently, with some people, dreams in which you are able to control what happens.  If such a thing were commonplace, who would need virtual reality or computer games, when every night you could create your own reality and then interact with it as if it were real?

The first step toward making such a thing possible for ordinary schmoes like myself, who dream frequently but never lucidly, may just have hit the market.  Called "Remee," the product looks like a sleep mask, but on the inside of the mask are six red LED lights.  Even with your eyelids closed, your eyes receive enough light to remain aware of your surroundings, and when the lights activate -- late in the sleep cycle, when you are most likely to be in REM (Rapid Eye Movement, the stage of sleep in which you dream) -- your brain becomes aware of them.  At that point (so the theory goes), your perception of the red lights becomes a signal, alerting you to the fact that you're dreaming.  From there, the lucid dream is initiated.

So, the lights act a little like the totem objects in Inception -- giving you an anchor, something that clues you in with regards to what is going on.  But unlike the totem objects, whose purpose was to check to see if you were dreaming so you could get out, if need be, here the purpose is to let you know that the fun is about to begin.

The inventors of Remee, Duncan Frazier and Steven McGuigan, told The Daily Mail (read the story here) that their tests have indicated that the lights are unlikely to cause seizures or any other ill effects.  If they fire during non-REM sleep, for example, the brain simply ignores them -- as it does if a faint light (say the distant headlights of a car) shine briefly into your bedroom window at night.

Remee masks are priced at $95 each, and are available here.  Frazier and McGuigan report that since Remee masks first came on the market, they've received over 7,000 orders.

Me, I find this intriguing, but I do wonder about what long-term (possibly psychological) effects such a thing might have, as we still don't have much of an idea what dreaming actually does.  That dreams are important seems obvious, given their ubiquity amongst mammal species -- both of my dogs clearly dream, apparently about chasing squirrels judging by how their feet move and the little muffled woofing noises they make.  Features that are widespread amongst many different, distantly-related species are called evolutionarily conserved features, and the usual interpretation is that they have been maintained through evolutionary history because they serve some sort of essential purpose.  As such, you have to question the wisdom of monkeying around with something like dreaming until we know more about it.

Be that as it may, if I had a Remee mask, I'd definitely try it.  Whatever harm it might do, I would guess, is unlikely to happen from occasional use.  And if you decide to get one, do let me know by posting here what your results are.  Given the unsettling nature of many of my nightly forays into the dream world, it might be nice to have a strategy for taking charge and having a little fun.