Sleep deprivation affects the brain in ways that can be detected through imaging. Lack of sleep alters the brain's metabolism; it produces less growth hormone. Some parts of the brain become much less active as your sleep debt grows, while others become busier as they attempt to compensate.
For instance, the temporal lobe -- which assists in language processing -- becomes less active the longer you stay awake, while a related area -- the parietal region -- partially makes up for the slack by becoming more active [source: UC San Diego Health System].
One study showed sleep-deprived subjects exhibited diminished activity in the regions of the brain that handle mathematics. No other region stepped up to help, so participants did much worse when doing mathematics on little sleep.
Without sleep, you also have slower reaction times and more difficulty with fine motor skills, which are controlled by the brain's motor cortex in the rear of the frontal lobe. And you become more impulsive and less inhibited [source: Anderson]. Combined with all the other detrimental effects of sleep deprivation, diminished ability to make good decisions can lead to lots of trouble.
Nobody knows this better than casinos, which benefit most when you're not thinking clearly. Casinos use several tricks to reduce your awareness of the passing of time and keep you on the floor, surrounded by opportunities to lose money. There are no clocks or windows in most casinos, and it's hard to find an exit.
One of the cognitive difficulties we encounter with sleep deprivation is an inability to assess our cognitive difficulties. The sleep-deprived just can't recognize the effects of sleep deprivation. So the likelihood of making risky decisions increases. This situation is especially dangerous in professions that offer little margin for error, such as law enforcement, heavy industry, health care or fire and rescue.
Compared with those who get seven or eight hours of sleep per night for a week, those who sleep only five hours a night make riskier decisions, pay less attention to negative consequences and focus more on short-term gains [source: Stevens]. While normally we approach risk in a defensive manner -- guarding against losses -- sleep deprivation makes us more likely to go for the gains confidently and disregard other consequences. In other words, we're more likely to place a large bet at the roulette table and let it ride.
Read on for lots more information about sleep deprivation that may keep you up.
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- Christensen, Misty Marie. "Effects of alcohol intoxication and sleep deprivation, on concentration, reaction time and driving simulation tasks." Washington College Psychology Senior Capstone Experience. Jan. 31, 2008. (July 20, 2011) http://dspace.nitle.org/handle/10090/3835
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- National Sleep Foundation. "How Much Sleep Do We Really Need?" (July 20, 2011) http://www.sleepfoundation.org/article/how-sleep-works/how-much-sleep-do-we-really-need
- Palmer, Brian. "Can You Die From Lack of Sleep?" Slate. May 11, 2009. (July 20, 2011) http://www.slate.com/id/2218092/
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- Stein, Anne. "Lack of sleep contributing to obesity." Chicago Tribune. June 29, 2011. (July 20, 2011) http://www.latimes.com/health/sc-health-0629-sleep-20110629,0,3551358.story
- Stevens, M. Suzanne, M.D. et al. "Normal Sleep, Sleep Physiology, and Sleep Deprivation." Medscape Reference. (July 20, 2011) http://emedicine.medscape.com/article/1188226-overview#a30
- The Franklin Institute. "The Human Brain: Renew- Sleep and Stress." (July 20, 2011) http://www.fi.edu/learn/brain/sleep.html
- The University of Chicago Medical Center. "Sleep loss boosts appetite, may encourage weight gain." Dec. 6, 2004. (July 20, 2011) http://www.uchospitals.edu/news/2004/20041206-sleep.html
- UC San Diego Health System. "Brain Activity is Visibly Altered Following Sleep Deprivation." July 29, 2002. (July 20, 2011) http://health.ucsd.edu/news/2000_02_09_Sleep.html
- Duke University Medical Center. "Sleep-Deprived People Make Risky Decisions Based On Too Much Optimism." ScienceDaily. March 21, 2011. (July 30, 2011) http://www.sciencedaily.com/releases/2011/03/110308172942.htm
- Venkatraman, Vinod et al. "Sleep Deprivation Biases the Neural Mechanisms Underlying Economic Preferences." Journal of Neuroscience. March 9, 2011. (July 20, 2011) http://www.jneurosci.org/content/31/10/3712.abstract
- WebMD. "Are You Getting Enough Sleep?" Feb. 9, 2009. (July 20, 2011) http://www.webmd.com/sleep-disorders/guide/sleep-requirements
- WebMD. "Understanding Insomnia -- Treatment." Oct. 25, 2010. (July 20, 2011) http://www.webmd.com/sleep-disorders/understanding-insomnia-treatment