It's no secret that a night of not-enough-sleep makes us feel tired, stressed and all-around grumpy the next day. And now, researchers have found a molecular reason for why our bodies need to "make up" for that lost sleep -- at least, in worms.
The findings, published in the journal Current Biology, were conducted in nematode round worms called Caenorhabditis elegans (C. elegans). Even though the worm is an invertebrate, many scientists study these animals because observations in these creatures often apply to vertebrate animals, like humans.
Researchers examined the worms as they were in a developmental state of "lethargus" -- basically the worm equivalent of sleep, since worms don't sleep like humans do. They manipulated the worms so that they were unable to get any "sleep" during this phase. Researchers found that when the worms were "sleep"-deprived, a specific protein then activated genes known to play a role in stress. Scientists tried "knocking out" this gene, and found that when they did so, the worms no longer needed to make up for the exhaustion felt after being "sleep"-deprived (a concept called sleep homeostasis).
But researchers noted that while this may seem like a good thing -- hey look, no consequences of sleep deprivation! -- up to half of the worms whose genes were manipulated ended up dying.
"There's something important about being able to mount a homeostatic behavioral response," study researcher Dr. David Raizen, M.D., Ph.D., who is an assistant professor of neurology at the University of Pennsylvania, said in a statement. "We don't know what that is, but it's clearly important to the animal."
For more potential effects of sleep deprivation, click through the slideshow:
...Increase Stroke Risk
Even without the typical risk factors, like being overweight or having a family history, short sleep can up your risk for stroke, according to 2012 research. Adults who regularly slept fewer than six hours a night had <a href="http://www.huffingtonpost.com/2012/06/11/sleep-stroke-risk_n_1586837.html">four times the risk of stroke symptoms</a>, HuffPost reported.
...Lead To Obesity
Too little sleep can spur some less-than-ideal food choices, including <a href="http://www.huffingtonpost.com/2013/02/25/sleep-portion-sizes-deprivation-food-calories_n_2735497.html">serving yourself larger portions</a>, and a hankering for junk food, thanks to some complicated hormonal changes that occur when you don't get sufficient shuteye. It seems that six hours of sleep or less <a href="http://www.huffingtonpost.com/2012/10/26/sleep-deprivation-obesity-leptin-ghrelin-insulin_n_2007043.html">bumps up production of the hunger hormone ghrelin</a> and limits leptin, which helps you balance your food intake, according to a 2012 review of 18 studies of sleep and appetite.
...Up Diabetes Risk
A pair of small studies from 2012 examined the link between poor sleep and insulin resistance, a telltale risk factor for diabetes. One found that among healthy teenagers, the <a href="http://www.huffingtonpost.com/2012/10/03/sleep-insulin-resistance-teens_n_1929374.html">shortest sleepers had the highest insulin resistance</a>, meaning the body is <a href="http://diabetes.niddk.nih.gov/dm/pubs/insulinresistance/#resistance">not using insulin effectively</a>, according to the National Institute of Diabetes and Digestive and Kidney Diseases. The second study examined fat cells, in particular, and found that cutting back on sleep <a href="http://annals.org/article.aspx?articleid=1379773">increased insulin resistance in these cells</a>, even when <a href="http://news.health.com/2012/10/15/sleep-deprivation-insulin-resistance/">diet and calorie intake were restricted</a>, Health.com reported.
...Fuel Memory Loss
You probably know that on the days when you are most tired, you're forgetful and unfocused -- but sleep deprivation can lead to <a href="http://www.sciencedaily.com/releases/2013/01/130127134212.htm"><em>permanent</em> cognitive issues</a>. The less we sleep, the less we benefit from the memory-storing properties of sleep. But additionally, a lack of sleep can cause <a href="http://www.huffingtonpost.com/2013/01/28/sleep-deprivation-memory-loss_n_2566999.html">"brain deterioration,"</a> according to a 2013 study, which may at least in part explain memory loss in seniors.
At least in rats, long-term <a href="http://ebm.rsmjournals.com/content/237/9/1101.full">sleep deprivation seems to contribute to osteoporosis</a>, according to a 2012 study. Researchers found <a href="http://www.huffingtonpost.com/2012/09/26/sleep-deprivation-bones-marrow_n_1898610.html">changes to bone mineral density and bone marrow</a> in the rodents when they were deprived of shuteye over a period of 72 days. "If true in humans, and I expect that it may be, this work will have great impact on our understanding of <a href="http://www.eurekalert.org/pub_releases/2012-09/sfeb-los_1091812.php">the impact of sleep deprivation on osteoporosis</a> and inability to repair bone damage as we age," Steven R. Goodman, Ph.D., editor-in-chief of Experimental Biology and Medicine, said in a statement.
...Increase Cancer Risk
A small (but growing) body of research suggests that short and poor sleep can up risk for certain types of cancer. A 2010 study found that among 1,240 people screened for colorectal cancer, the 338 who were diagnosed were <a href="http://onlinelibrary.wiley.com/doi/10.1002/cncr.25507/abstract">more likely to average fewer than six hours of sleep</a> a night. Even after controlling for more traditional risk factors, polyps were more common in people who slept less, according to the study. Getting just six hours of sleep a night has also been linked to an <a href="http://www.huffingtonpost.com/2012/09/06/sleep-breast-cancer-aggressive-deprivation_n_1854658.html">increase of recurrence in breast cancer patients</a>. The study's author has pointed to more and better sleep as a possible pathway of reducing risk and recurrence.
...Hurt Your Heart
The stress and strain of too little sleep can cause the body to produce more of the chemicals and hormones that can lead to heart disease, according to 2011 research. The study found that people who slept for six hours or less each night and have problems staying asleep had a 48 percent <a href="http://www.sciencedaily.com/releases/2011/02/110208091426.htm">higher risk of developing or dying from heart disease</a>.
It's not just heart problems that can lead to sleep-deprivation-related death. In fact, <a href="http://healthland.time.com/2010/09/02/lack-of-sleep-can-cause-depression-weight-gain-and-even-death/">short sleepers seem to die younger</a> of any cause than people who sleep about 6.5 to 7.5 hours a night, TIME reported. A 2010 study examined the impact of short sleep on mortality and found that <a href="http://www.journalsleep.org/ViewAbstract.aspx?pid=27894">men who slept for less than six hours of sleep a night were four times more likely</a> to die over a 14-year period. The study's authors called this link "a risk that has been underestimated."