Consequences of Lost Sleep

Experts recommend getting eight hours of sleep each night but most Americans get six-and-a-half. That 90 minutes of lost sleep builds up in what researchers call "sleep debt," the accumulated effects of lost sleep that remain until they are made up. Sleeping in an extra two hours over the weekend will do little to mend damage from six or more hours of accumulated sleep debt. Going to bed early will ultimately enable you to enjoy more hours of life.

Frontal Cortex Impairment

• Brain cells misfire when not properly rested. Over time, the buildup of sleep debt causes a loss of both brain power and higher-level cognitive functions. Sleep-deprived people have difficulties thinking creatively, and when they do think of something, they have difficulty expressing it clearly since the frontal cortex also controls verbal ability. Sleep deprivation further causes delayed reaction times. These factors explain Harvard Medical School's Division of Sleep Medicine's estimate that sleep deprivation annually causes approximately 1 million vehicle crashes, 500,000 injuries and 8,000 deaths in the U.S.

Mood

• According to a 2002-2003 University of Pennsylvania study, people getting less than five hours of sleep each night feel stressed, angry, anxious and sad at higher levels. Negative moods adversely affect ability to sleep, creating a vicious cycle. Healthy sleep patterns are the cure. The same study proved that consistently getting a good night's sleep improves mood and overall physical health.

Emotion

• Researchers at the University of California Berkeley conducted a study in 2007 comparing reactions to emotionally provocative images; the two groups included regularly rested people and individuals awake for 35 hours. The sleep-deprived individuals reacted much more emotionally than the control group, and it was found their amygdala, the center for emotion in the brain, was 60 percent more active than the control group's. According to Berkeley psychologist Matthew Walker, this suggests sleep loss can cause psychiatric disorders; it was previously thought psychiatric disorders caused sleep loss.

Obesity and Disease

• An ongoing University of Bristol study begun in 1989 has shown people who consistently sleep less than five hours each night had 16 percent less leptin -- a product of fat cells -- and 15 percent more ghrelin -- an appetite stimulant-- than people who slept an average of eight hours nightly. Such changes in appetite hormones, combined with sleep loss, can contribute to obesity.

  Sleep deprivation causes less production of white blood cells, greatly weakening the immune system and increasing chances for disease.