Though we all have varying needs for sleep (one person's five-hour beauty sleep may leave another person drowsy), you should generally get between seven and nine hours of sleep in a single day. You create a sleep debt when you fall an hour or two short of your needed sleep day after day. Sleep deprivation over the course of a week can lead to cognitive difficulties that are similar to those experienced by stroke patients [source: Stevens]. The result can be dangerous for those working long hours. Studies show medical residents experience more accidents after putting in long shifts [source: Durmer].
Drivers who are sleep deprived are as bad as -- and sometimes worse than -- intoxicated drivers in studies that have tested both groups using driving simulators. According to the National Highway Traffic Safety Administration, there are around 100,000 traffic accidents a year due to sleep deprivation and 1,550 fatalities [source: Breus].
Sleep deprivation affects your body and mind in myriad ways. As a sleep debt builds, your ability to concentrate decreases. Thinking becomes labored, and vision becomes blurry. You may experience headaches or feel especially agitated or moody. You start to forget things.
The immune system takes a hit as well. When sleep deprived, you have fewer white blood cells, and those you do have aren't very effective in destroying unwanted antigens in the body. Your body temperature drops, and your heartbeat can become erratic. The greater the sleep debt, the more difficult it is to process visual information.
You're feeling weak, distracted, foggy and upset. You have a headache, and you can't see straight. Think these are bad circumstances for making decisions? Research shows that when you're sleep deprived, there's more activity in the parts of your brain that analyze positive outcomes and less activity in parts responsible for weighing negative outcomes.
Whether you're caring for patients in a hospital, pulling a double shift at the factory, piloting a passenger plane or driving a truck, you're more likely to make an error [source: Durmer].
In what other ways does sleep deprivation affect decision making? Odds are, you're not ready for a weekend in Vegas.
Danger Behind the Roulette Wheel
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.
- Anderson, Clare and Charlotte R. Platten. "Sleep deprivation lowers inhibition and enhances impulsivity to negative stimuli. " Behavioral Brain Research. March, 1, 2011. (July 30, 2011) http://www.sciencedirect.com/science/article/pii/S016643281000656X
- Breus, Michael J., Ph.D. "Chronic Sleep Deprivation May Harm Health." WebMD. Mar. 15, 2006. (July 20, 2011) http://www.webmd.com/sleep-disorders/guide/important-sleep-habits
- 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
- Downs, Jenny R. "How Sleep Deprivation Affects Psychological Variables Related to College Students Cognitive Performance." Jan. 11, 2011. (July 20, 2011) http://reviewessays.com/print/Sleep-Deprivation-Affects-Psychological-Variables/30747.html
- Durmer, Jeffrey S. "Neurocognitive Consequences of Sleep Deprivation: Sleep Deprivation and Accident Risk." Seminars in Neurology. March 2005. (July 30, 2011) http://www.medscape.com/viewarticle/503105_2
- Ledoux, Sarah. "The Effects of Sleep Deprivation on Brain and Behavior." Jan. 3, 2008. (July 20, 2011) http://serendip.brynmawr.edu/exchange/node/1690
- Lieberman, H.R. "Effects of caffeine, sleep loss, and stress on cognitive performance and mood during U.S. Navy SEAL training." Psychopharmacology. Nov. 2002. (July 20, 2011) http://www.ncbi.nlm.nih.gov/pubmed/12424548
- 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/
- Roy-Byrne, Peter P., M.D. et al. "Effects of One Night's Sleep Deprivation on Mood and Behavior in Panic Disorder." Archives of General Psychiatry. Sept., 1986. (July 20, 2011) http://archpsyc.ama-assn.org/cgi/content/abstract/43/9/895
- 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