Here we go again.  Talking about sleep.  Like we really know about what we talk.

Sure, you hear over and over again that we need 8 hours of sleep.  How do we know that?  From correlations- at best- and not from direct data.

Now, a slew of researchers from the University of Oxford may be able to start providing answers.   Drs. D Pimentel, JM Donlea, CB Talbot, SM Song, AJF Thurston, and G Miesenbock published a short paper in Nature that may provide a way to obtain real data.

The study described their efforts to find the switch- whatever it is that tells the body to sleep.  This switch is activated when the body feels it needs rest- and turns off when it’s time we should awaken.   But, while we now know there is a switch- and where it is located- we have no clue what turns that switch on…. yet.

Because as the researchers reported, we don’t go to sleep when we get tired- because we don’t know how to (scientifically) determine what ‘being tired’ means.  It’s why some of us (moi?) don’t retire until the wee, wee hours of the morning (and wake up right before dawn) and others of us hit the sack at 9 PM and are still slumbering at 7 AM.

But, we do know that our circadian rhythm- the 25 (yes, about 25 hours- except for nocturnal animals) hour clock that governs our body functions- is part of the control switch.  This biological rhythm or oscillation is part of all the daily, tidal, weekly, seasonal, and annual rhythms that form our life cycles (chronobiology).   This circadian clock monitors the temperature and sunlight to help us discern when we should sleep.

And, now we know there is a sleep homeostat- the one that monitors some sort of hidden signal- that builds up during our waking hours.  Once it approaches the saturation level (whatever that is), our brain neurons (sleep controls) kick in and we are off to dreamland.   As we sleep, that mysterious compound (or compounds) that activated the switch dissipates and we are ready to wake up.  (The technical term for this is called a feedback loop.)

These two systems (circadian and homeostatic) were first described by Borbély about 30 years ago.  He described sleep and wakefulness as separate- but interacting- cycles.  Drs. Donlea, Pimentel, and Miessenbock first described the neural sleep mechanism a few years ago in Neuron.  They identified the gene crossveinless-c (cv-c) as the locus of homeostatic control.

They found that electrical activity in a cluster of cells of the fruitfly called the dorsal fan-shaped body (dFB), an ionic channel, was the key control.   They found it because while sleeping, a molecule remained inactive at the neural center; but when dopamine was released, the molecule reached the cell’s exterior portion, short-circuiting the dFB complex and the flies were awake. If they turned the ion channel completely off, the flies remained asleep; not waking up.  (No Prince Charming to kiss them and cause them to awaken.)

Being able to examine this region and manipulate the sleep homeostat at the molecular level will provide the means to discern what “tired” really means.  This will advance our knowledge of sleep and its effect on the body, truly revealing what we all want to know:  How much sleep do we really need?

Oh, and given the fact that these researchers found the channel, they got to name it.  And, with whimsy, they did- it’s “Sandman”.

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