Anyone who has pulled an all-nighter knows it is possible to be tired without being sleepy. The body slows and concentration slips, even as thoughts spin toward a manic blur. It feels as though the sleep-deprived brain is actually becoming more active. And indeed it is, according to a recent study in the journal Cerebral Cortex.

Marcello Massimini, a neurophysiologist at the University of Milan in Italy, found that the brain becomes more sensitive as the day wears on. The experiment, he explains, is like poking a friend in the ribs to see how high he jumps. Massimini prodded brain cells in the frontal cortex with a jolt of electricity, delivered via noninvasive transcranial magnetic stimulation. Then he observed how the rest of the brain responded, comparing results from subjects who had been awake for two, eight, 12 or 32 hours. “I'm sure if you bump your friend when he's sleep-deprived, he's going to jump higher,” he says. The sleep-deprived brain, it turns out, also gets jumpy, responding to the electrical jolt with stronger, more immediate spikes of activity.

The results jibe with a widely held theory that while we are awake, our neurons are constantly forming new synapses, or connections to other neurons, which ramps up the activity in our brain. Many of these connections are irrelevant, but the only way to prune them is by shutting down for a while. The theory explains why it is difficult to cram new information into a sleepy brain. But it also helps to explain some unusual medical observations: epileptics are more likely to have seizures the longer they stay awake, and severely depressed patients with abnormally low brain activity sometimes improve after skipping sleep. “You keep them awake for one night, and, incredibly, they get better,” Massimini says.

16 Comments

1. 1. jtdwyer 10:31 AM 6/30/12

   "The results jibe with a widely held theory that while we are awake, our neurons are constantly forming new synapses, or connections to other neurons, which ramps up the activity in our brain. Many of these connections are irrelevant, but the only way to prune them is by shutting down for a while. The theory explains why it is difficult to cram new information into a sleepy brain."
   
   Here's a more meaningful theory to account for why memory functions degrade in the absence of sleep, based on information systems.
   
   Physical storage capacity can best be partitioned into two pools - short term and long term. Short term memory is optimized to most quickly store large volumes of new information by simply sequentially journaling raw data. However, the size of this physical storage partition is fixed to support roughly the amount of new information expected to be acquired in one day.
   
   Long-term memory is organized much differently, to minimize the amount of physical storage needed and to optimize retrieval effectiveness. This more complex organization of memory requires additional processing time, most readily available when the system is not fully operational - during sleep.
   
   To optimize storage efficiency individual memory components are compressed and encoded - redundant data may be linked to allow many references to a single memory storage instance. As a result a new memory may be encoded as a string of references to existing common memory elements. This explains why existing memories can change over time, and why old memories are randomly recalled during sleep - producing the dream state.
   
   Optimization of memory recall requires the maintenance of many indices allowing direct access of memory lists by various connotations. Situations that are likely to result in pain can be quickly recalled directly, for example.
   
   All the additional processing required to prepare journaled memories for effective long term storage requires time - when the memory system is otherwise inactive. Migration of journaled short-term memories to long term storage, freeing up physical storage allocated to short-term memory, can only occur during system down-time.
   
   Depriving an individual of sleep eventually exhausts the fixed storage capacity allocated for short term memory, preventing the acquisition of new memories. Memory system operation eventually degrades because recently acquired memories cannot be accessed effectively.
   
   This functional description of memory processing requirements is more useful than 'having too many neurons connected'.

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2. 2. promytius 01:17 PM 6/30/12

   Does this research cure morons who go around poking people in the ribs just to see how high they will jump?

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3. 3. jsmith2012 in reply to jtdwyer 02:59 PM 6/30/12

   Is there any evidence that the brain works this way.

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4. 4. jtdwyer in reply to jsmith2012 04:21 PM 6/30/12

   Well, my baseline is a study that reportedly indicated that "the brain becomes more sensitive as the day wears on" which jibed with a theory that the waking brain connects too many neurons.
   
   But, to answer your question, this functional description can explain the empirical evidence that memories are 'randomly' recalled during dreams, why the creation of new memories becomes inhibited, why recently stored memory access becomes degraded and why these conditions are alleviated by eventual sleep.
   
   The 'theory' mentioned in the article says that too many neurons are produced and they can only be trimmed while sleeping. I don't find any hint of supporting evidence or even rationale...
   
   Do you have some evidence that the brain doesn't work as I described?

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5. 5. Bops in reply to promytius 07:06 PM 6/30/12

   Probably not, because there are so many bullies that think it's also funny to buff someone behind the head.

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6. 6. jtdwyer in reply to jsmith2012 10:31 PM 6/30/12

   BTW, sorry if my reply was overdone - my heart meds interfere with my sleep schedules, sometimes making me overly sensitive :-)

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7. 7. Loubarouba 05:46 AM 7/1/12

   and severely depressed patients with abnormally low brain activity sometimes improve after skipping sleep. “You keep them awake for one night, and, incredibly, they get better,”
   
   This actual holds some weight to it as I was quite depressed for about a two and a half years after having the closest person to me pass away. Where I ended up in a somewhat destructive downward spiral, not caring about anything really, I basically became totally desensitized to my surroundings and any emotions that came with it, not any real happiness or sadness, everything just became extremely dull and grey.
   How I came out of it was due to a project being due, now because I'm pretty OCD, I took helm to a major group project and did 80% of the project myself and also because I'm a procrastinator I ended up doing the bulk of it last minute pulling an all-nighter to finish it with the help of energy drinks and a NO2/creatine supplement. After being awake for 36+ hours I fell right asleep and then woke up 9 hours later feeling the best I've felt since the death, it worked wonders on me, I was quite surprised with the effects and would recommend trying an all-nighter to reverse depression.

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8. 8. jtdwyer in reply to Loubarouba 06:04 AM 7/1/12

   As I understand, patients diagnosed as 'severely depressed' with abnormally low brain activity are generally dysfunctional and unable to care for themselves. I hope you continue to feel better...

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9. 9. Owl905 08:47 AM 7/1/12

   The obvious next step would be invasive electrical jolts. On the upside, it should make staying awake easier, what with the added pain and all.

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10. 10. TimUK in reply to jtdwyer 08:58 AM 7/1/12

    jtdwyer, your thoughts resonance with some ideas I wrote a while back.
    http://neurosciencethoughts.blogspot.co.uk/
    
    I am moving to the view that we may not remember 'facts' per se but instead 'experiences' - the information *and* scenario handled as one. The job of sleep being a necessary and timely correlation of episodic / short term / working experience to reinforce by *copying* (with errors) sufficiently relevant experiencial scenarios into deep memory.
    

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11. 11. jtdwyer in reply to TimUK 02:00 PM 7/1/12

    Thanks for the link - I agree the scenarios are quite similar. I think it's also very interesting that we arrive at similar conceptions from completely different perspectives: I'm discussing generalized memory management functional issues primarily based on well understood information management requirements and methods.
    
    I think the idea that memory storage processes identify elements within a new experience that are common with many experiences is very important. In this way common elements can be stored as links to a shared single memory instance (snippet) - that would be crucial to reducing global physical storage requirements, explain why old memories must be recalled to store new experiences and how and why old memories may be altered - to best fit all shared invocations.
    
    An analogy might be that everyone stores a single web page that contains their own image - any memory that references your own image would access that shared page. Over the years that self image might become a vague composite of your appearance as a young, middle aged and old person - still accessed by all memorizes that include your self image...

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12. 12. Magoonski 11:20 PM 7/1/12

    I actually work the overnight shift three days a week. In the mornings, I do catch a kind of "second wind," which allows me to make it through 20 hours of being awake on only one cup of tea. I can atest to feeling more hyper/silly/jumpy (better than being drunk) the longer I'm forced to stay up. I also notice that after a while I completely go blank on anything that happened more than four to six hours earlier. Granted, I can eventually remember but usually I have to sleep first.
    Too bad the whole article isn't posted online, I would love to compare my own experiences to this article.

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13. 13. Shoshin in reply to Magoonski 08:52 AM 7/2/12

    I agree with your comments. I work in a field where it is not uncommon to go 36 or 48 hours without sleep and then be responsible for decisions costing hundreds of thousands or even millions of $$.
    
    After 36+ hours I shouldn't be trusted with anything sharper than a rubber ball.

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14. 14. jgrosay 06:03 PM 7/2/12

    Yeah!: this is true, sleep deprivation, and more specially if deprivation is selective or more intense of some sleep phases, is a deprivation of a physiologically needed activity of our brain that it activates so much your mind that you can become completely insane!

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15. 15. Alenz 06:09 PM 7/2/12

    Sleep deprivation only brings harm to health, nothing else! Or do you think positive if scare tremendously with something not so scary?
    Imagine the heart risk in these experiments, although that should be at the expense of the suffering of helpless animals. Good would be these tortures with politicians of brézil!

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16. 16. 00Marx 12:30 AM 7/3/12

    Interesting article. You should look into how sleep deprivation affects artists and the creative process. From my own experience I am more creative when I have been up for more than 24 hours. It's like my brain craves the longer stretches and hesitation and inhibitions drop away and everything becomes very crisp. When I have a deadline I can just push past the need for sleep and just work 36-48 hours without a problem as long as I stay busy and eat healthy food. Caffeine spikes the energy levels too severely and makes me jittery so I avoid it when I do these multi-day all-nighters. 110 hours is the most I've ever stayed awake and still been functional.

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