Med thumb what happens when we don t sleep main
The scientific literature is unanimous: you gotta get some sleep. How much is dictated by a biological imperative, though, is a little more up for debate, especially for non-human species. For instance the creepy-cute sloth bags up to 20 hours of shuteye a day, while sharks, which need to be in constant motion in order to resuscitate, never fall into deep sleep (which may explain their tendency toward grumpiness). 
 
The notion that animals actually must sleep is one that has long confounded scientists, with research uncovering endless new benefits attributable to quality sleep, as well as the many deficits related to its absence. And they are legion. Here's a look at the punishment you sustain for skimping on sleep, from the late night out, to chronic sleep loss, to idiotic record-breaking feats.
 

Skip out on a few hours? Prepare to drag ass for a few days

Go out to for work drinks past the witching hour and the next day your excesses will be apparent. Hangover or no, in deviating from your body's normal sleep pattern you will feel the effects because you will miss out on crucial REM-sleep patterns, which tend to happen earlier in an overnight sleep cycle. So even if you get a chunk of sleep in, it's not the quality sleep your body craves. This type of missed sleep is extremely common in our night owl society, and its effects are suitably detrimental: you aren't as alert, have less stamina, and basically drag ass for a couple days. That may not sound threatening, but note that the National Highway Transit Safety board attributes up to 100,000 car accidents per year to overtired or "drowsy driving," and ranks the condition on par with drunk driving.  

Been cutting sleep short every night for a few weeks? You're doing some real damage. 

A recent Harvard study of sleep deprivation and performance found that, contrary to perceived wisdom, once you cut your sleep short, there's no magical way to get it back. The study futzed with subjects sleep schedules and then tested the outcome, as well as attempts to regain normal faculties. The results were not promising. The researchers found that the most common aid to sleepiness — a nap — does nothing to combat the sorts of chronic shortened sleep that many of us consider normal, or about 6 hours a night. In fact, after a couple weeks of abbreviated sleep schedules of the sorts regularly experienced by doctors, cops, and truckers, performance was still on par with having pulled an all-nighter even if you were able to pack in extra 10 hours of crash time. 
 
Other studies have shown that those of us who trudge through life with abbreviated sleep schedules — about 43 percent of us, according to a 2011 Sleep Foundation study— are actually doing real and permanent physical and psychological damage. Besides the obvious decrease in alertness and reduced work performance, researches have found hard links to an increased risk of obesity, diabetes, heart disease, as well as psychological conditions like anxiety and depression. 
 
A couple weeks of abbreviated sleep schedules of the sorts regularly experienced by doctors, cops, and truckers, performance was still on par with having pulled an all-nighter even if you were able to pack in extra 10 hours of crash time.
 

Go three days with no sleep? Expect to experience psychosis

Research sleep deprivation and all roads quickly lead to Randy Gardner, the last official world record-holder for thwarting sleep until Guinness stopped keeping records of such dangerous feats. It seems that back in 1964 the 17-year old utterly crushed the competition at a dance-a-thon by staying up for eleven-plus days in a row (note this was pre-cocaine/ecstasy/molly). What makes his feat especially noteworthy is that it was monitored the entire time by a team of sleep researchers. He did suffer short term effects, but amazingly, Gardner took a 14-hour sleep afterward and reportedly suffered no long-term ill effects. 
 
After three days you may dream while still awake, which is the definition of psychosis.
 
His experience is somewhat different to what torture victims who are routinely denied sleep have endured. One anti-torture advocate who had experienced forced deprivation says that within a couple days you start to hallucinate, and after three days you may dream while still awake, which is the definition of psychosis. Within a week you become derailed from the sense of time and are effectively insane. That said, no outer limit has ever been established as a fatal amount of sleep loss, though certainly there is anecdotal evidence, such as the Taiwanese man who was found dead in an internet cafe from heart failure after three straight days of playing video games. 
 

If your body can't sleep, you're screwed.

History books bulge with stories of figures who changed the arc of human progress by burning the midnight oil. Many of them were insomniacs — think of Van Gogh or Lincoln — and many of them were, to be gentle, troubled.
 
Insomnia is a pernicious ailment plaguing many sufferers for life, and with many causes, both physical and psychological. While most insomnia is actually an inability to sleep for extended periods, the extreme expression of the disease is a blessedly rare genetic condition dubbed F.F.I. or fatal familial insomnia. Onset occurs around middle age, and as it progresses it leads to panic and anxiety, hallucinations, eventual total sleep loss, and then a rapid decline into madness and eventually death within a couple years. It is, perhaps ironically, a real-life nightmare. Experts believe just 40 families and perhaps 100 individuals suffer from the condition worldwide, though that is likely of small comfort to the insomnia pondering his odds in the middle of the night