Are you getting enough rest? You probably know that poor sleep is bad for you, but a new study shows exactly how your body suffers from a lack of sleep.

A new study shows how just one week of insufficient sleep alters the normal functions of over 700 genes, causing a wide range of serious negative effects on your health.

Previous studies have linked a long-term sleep deprivation with obesity, heart disease, cognitive impairment, and other negative health outcomes, but the molecular mechanisms that lead to such declines were not fully clear until now.  

In one of the first studies of the effects of sleep deprivation on the human "transcriptome," or the set of messenger molecules for the human genome, British researchers have showed that over time, insufficient sleep directly alters gene expression responsible for processes like immune responses, stress, and metabolism, which have a wide range of negative downstream effects.

The study, conducted by scientists at Surrey University in England, was published online in the journal Proceedings of the National Academy of Sciences on Feb. 25, 2013.

The researchers examined gene expression in 26 healthy volunteers who were deprived of sleep.

The participants in the sleep restriction condition were allowed only about 6 hours of sleep a night for seven consecutive nights, while the control group was allowed 10 hours of sleep.

At the end of the week, both groups were kept awake for a 40-hour period during which blood RNA samples were collected, then allowed 12 hours of constant sleep to recover.

Both groups were observed in a sleep center, with their sleep quality recorded throughout with standard polysomnography measures. A battery of tests was used during their waking hours to assess their cognitive performance and how they felt about their sleep quality each day.

In addition, researchers assayed levels of the hormone melatonin, which regulates biological rhythm and sleep cycles.

RNA analysis of the blood samples revealed that 711 genes were up- or down-regulated by insufficient sleep, meaning that their normal activity either decreased or intensified.

Every gene, or unit of DNA, is responsible for the creation of a protein involved in some bodily process. RNA is the "messenger chemical" that leads from DNA (the unchanging genetic code) to protein creation. If gene expression is turned up or down from its normal levels, it can cause a domino effect that leads to dramatic changes in the human body.

The genes altered by sleep deprivation in this study were involved in regulating sleep homeostasis, stress response, and metabolism.

Many of the malfunctioning genes were involved in maintaining the circadian rhythm, or "biological clock" -- that is, the timing of biological processes that are supposed to happen at specific times during a 24-hour cycle.

Others were responsible for overall gene regulation, meaning that chronic sleep loss can cause even more negative changes than the ones directly identified in this study.

Sleep deprivation also caused participants to perform more poorly on tests of cognition, memory and attention.

The findings have strong indications for most people living in the industrialized world.

According to the Centers for Disease Control and Prevention (CDC), 30 persent of civilian adults in the United States -- over 40 million workers -- report getting only 6 hours of sleep or less per night.

This means that millions of Americans are susceptible to the long-term changes in metabolism, stress response, and immunity that can put them at risk for disease.

While the ideal length of a good night's sleep varies widely among individuals, studies indicate that most people need somewhere between 7 and 9 hours per night.