Lack of sleep far more harmful than thought: Study

Sleep deprivation is much more harmful to humans than previously thought, according to one of the largest sleep studies to date.

The study, published in the Journal of Experimental Psychology: General, is the first to assess how sleep deprivation impacts place keeping -- the ability to complete a series of steps without losing one's place, despite potential interruptions.

"Our research showed that sleep deprivation doubles the odds of making place keeping errors and triples the number of lapses in attention, which is startling," said Kimberly Fenn from Michigan State University (MSU) in the US.

"Sleep-deprived individuals need to exercise caution in absolutely everything that they do, and simply can't trust that they won't make costly errors. Oftentimes --like when behind the wheel of a car -- these errors can have tragic consequences," Fenn said in a statement.

By sharing their findings on the separate effects sleep deprivation has on cognitive function, Fenn and colleagues hope that people will acknowledge how significantly their abilities are hindered because of a lack of sleep.

"Our findings debunk a common theory that suggests that attention is the only cognitive function affected by sleep deprivation," said Michelle Stepan, MSU doctoral candidate.

"Some sleep-deprived people might be able to hold it together under routine tasks, like a doctor taking a patient's vitals," Stepan said.

However, the results suggest that completing an activity that requires following multiple steps, such as a doctor completing a medical procedure, is much riskier under conditions of sleep deprivation.

The researchers recruited 138 people to participate in the overnight sleep assessment -- 77 stayed awake all night and 61 went home to sleep.

All participants took two separate cognitive tasks in the evening, with one measuring reaction time to a stimulus.

The second task measured a participant's ability to maintain their place in a series of steps without omitting or repeating a step -- even after sporadic interruptions.

The participants then repeated both tasks in the morning to see how sleep-deprivation affected their performance, the researchers said.

"After being interrupted there was a 15 percent error rate in the evening and we saw that the error rate spiked to about 30 percent for the sleep-deprived group the following morning," Stepan said.

"The rested participants' morning scores were similar to the night before," she said.