Tuesday, October 7, 2014

Get Some Sleep - Your Brain Will Thank You

Sleeping may be the great American pastime. A survey from 2009 stated that over 1/3 of Americans  nap daily. Sure, 49% of Americans are professional football fans, but those games don’t occur every day, and I bet a bunch of those fans nap anytime the Jaguars are on TV.

The koala sleeps 18-22 hours a day. Their food
(eucalyptus leaves) is so difficult to digest that they
have to use a lot of their energy just to extract the
little bit of nutrition and carbohydrates from them.
This is fascinating, but I used the picture to suck you
in – they're just so darned cute!
I’ve never been much of a napper, but I live with three of them. My wife tells me that napping is just heavenly. My daughter agrees; she says sleeping late is what heaven dreams about. Unfortunately, a 2013 Gallup report found that 40% of Americans don’t get the recommended 7-9 hours of sleep each night. They only polled adults, so who knows how many kids are sleep-deprived.

We do need a considerable amount of sleep, but why? When I lose out on sleep, I find it hard to concentrate and I don’t have as much energy. I make much less sense when I’m tired, both in print and in … you know, person … like.... speaking. See this post for reasons we need to sleep.

As for kids, there are arguments now raging about how to be sure they get enough sleep. The National Institutes of Health recommends that elementary students get 10-12 hours of sleep each night. Middle school and high school students need at least 10 hr and 9-10 hr, respectively.

A movement is on to back off on the start times of middle school and high school. The American Academy of Pediatrics is recommending that high schools and middle schools start no earlier than 8:30 am. This confuses me. Won’t the kids just go to bed later? You’re not giving them more sleep, you’re just shifting their day. You want them to get more sleep? Keep handing out those worksheets in class. A different strategy might be needed, but the quest is a noble one.

It turns out that sleep isn’t just a good idea – your brain depends on it. Loads of new research is showing that brain function and even brain survival is tied to adequate sleep.

Current estimates are that only 8% of high school
students get adequate sleep on a regular basis. Does
that count the time they sleep in class? Many schools
have shifted the class day back in an effort allow them
more sleep time. I haven’t noticed a difference in
the kids at these schools.
Learning in school, or anywhere for that matter, is based on creating new neural pathways in your brain, and then reinforcing them to make them stronger. Moving new knowledge to long-term memory is based on a mechanism called long-term potentiation (LTP), where often used neural pathways begin to feedback and strengthen themselves.

The opposite is also true, in order to make the most of any new connections, you need to prune back (cause to degrade) the connections that you aren’t using. This is called long-term depression (LTD). The two mechanisms work together to help you learn, and their function is tied to adequate sleep.

Many studies have shown that sleep loss affects LTP and LTD, but a newer study indicates when it most likely to be a problem. In sleep-deprived mice, a learning session immediately followed by sleep deprivation was not as bad for long-term memory consolidation as was a learning session where the sleep deprivation was begun 1-3 hours later. Apparently, when you lose your sleep can matter more than how much sleep you miss.

So - learning is better when you have adequate sleep. But can too little sleep actually harm your brain? It turns out that yes, it can. A 2014 study from the University of Pennsylvania looked at neuron function in the locus coeruleus (LC), the part of the brain that works in alertness and problem solving.

Their experiments in a mouse model of sleep deprivation demonstrated that while a little sleep deprivation upregulated a protein (Sirt3) important for mitochondrial function, more sleep deprivation had the opposite effect. With too little sleep, the mitochondrial Sirt3 disappears and the cells can’t make ATP for energy. With no energy, they die off.

This is permanent, irreversible damage mediated by sleep deprivation. Ouch…. But wait, it gets worse. Sleep deprivation could hurt you another way. Depression is connected to sleep loss, and depression is definitely bad for your brain.

You’re looking at the hippocampus in cross section in
a regular (above) and depressed (below) person by
CT scan. The hippocampus looks like a seahorse, but
not from this angle. You can see the decrease in size
correlated with major depression.
A new study shows that depression affects the hippocampus, the part of the brain that works in long-term memory, emotional responses, and spatial organization. Connections between the different layers of the hippocampus can be lost, along with decreased communication structures on the neurons of those layers.  And this isn’t all.

Other studies indicate that patients with major depression have hippocampi that are up to 10% smaller than those in non-depressives. Loss of sleep makes you susceptible to depression or makes depression worse, and being depressed can kill your brain cells.

The above studies show that function is decreased when you don’t get enough sleep and you can do permanent damage to your brain. What if we take sleep loss to the nth degree, could it kill you? Yep.

Fatal Familial Insomnia (FFI) is a rare, genetic disease wherein individuals have a harder and harder time falling asleep. First they can’t sleep through the night and don’t enter REM sleep. Then they can only nap. At the end of the 10-18 month course of the disease, they can’t sleep at all; they enter into dementia and die.

The name of the disease is a little deceiving, it may not be the lack of sleep that kills you, although it does make life hard to endure. FFI is a prion protein disease, like Creutzfeldt–Jakob, mad cow disease, or Kuru. It’s the prion protein plaques that are the root of the problem and cause the disease. It just happens that the prion plaques from FFI first form in the parts of the brain that regulate sleep (the anterior hypothalamus and preoptic nucleus, see this post).

A great book that tells the story of prion protein
diseases, especially fatal familial insomnia is called
The Family That Couldn’t Sleep, by journalist D.T.
Max. I highly recommend it. It won’t put you to sleep.
A 2013 study showed that gene expression profiles in FFI patients are really screwed up in the thalamus and hypothalamus, including mitochondrial electron transport systems – the same type problem identified in the sleep loss and LC cell death study mentioned above.

FFI is found only in a few families, but it's devastating for them. There's no treatment, and sleeping pills seem to make it worse. It gets scarier - the disease doesn’t have to be genetic, it can spring up out of nowhere (called sporadic cases). And since it doesn’t become evident until adulthood, you could pass it on to your children before you even know you have it.

All this information makes me want to take a different attitude toward sleep. Find some time during the day to rest your eyes and make sure you get to bed at a decent time – it might just save your brain, or even your life.

Contributed by Mark E. Lasbury, MS, MSEd, PhD
As Many Exceptions As Rules

Zhang J, Zhu Y, Zhan G, Fenik P, Panossian L, Wang MM, Reid S, Lai D, Davis JG, Baur JA, & Veasey S (2014). Extended wakefulness: compromised metabolics in and degeneration of locus ceruleus neurons. The Journal of neuroscience : the official journal of the Society for Neuroscience, 34 (12), 4418-31 PMID: 24647961

Qiao, H., An, S., Ren, W., & Ma, X. (2014). Progressive alterations of hippocampal CA3-CA1 synapses in an animal model of depression Behavioural Brain Research DOI: 10.1016/j.bbr.2014.08.040

Prince TM, Wimmer M, Choi J, Havekes R, Aton S, & Abel T (2014). Sleep deprivation during a specific 3-hour time window post-training impairs hippocampal synaptic plasticity and memory. Neurobiology of learning and memory, 109, 122-30 PMID: 24380868

Tian C, Liu D, Sun QL, Chen C, Xu Y, Wang H, Xiang W, Kretzschmar HA, Li W, Chen C, Shi Q, Gao C, Zhang J, Zhang BY, Han J, & Dong XP (2013). Comparative analysis of gene expression profiles between cortex and thalamus in Chinese fatal familial insomnia patients. Molecular neurobiology, 48 (1), 36-48 PMID: 23430483

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