NEW YORK (Reuters Health) - Sleep deprivation may lead not only to bleary-eyed mornings, but clouded moral judgment as well, a study suggests.

Army researchers found that when they subjected a group of volunteers to two sleepless nights, the lack of shut-eye seemed to hinder participants' ability to make decisions in the face of emotionally charged, moral dilemmas.

The dilemmas in this case were hypothetical scenarios, and not actual events. But the study authors say the findings could have implications for people who are both routinely sleep-deprived and often need to make quick decisions in a crisis -- such as soldiers in combat and medical professionals.

Dr. William D. S. Killgore and colleagues at Walter Reed Army Institute of Research report the findings in the journal Sleep.

In recent years, brain imaging studies have found that an area called the ventromedial prefrontal cortex appears to play an important role in forming moral judgments. There's also evidence that sleep deprivation lowers metabolic activity in this brain region, Killgore and colleagues point out.

It's possible, they speculate, that sleeplessness slows the brain's ability to integrate cognitive and emotional information, which is needed to address serious moral dilemmas.

The researchers based their findings on tests of 26 healthy military personnel. The volunteers were presented with various scenarios, then asked whether a given course of action would be "appropriate" or "inappropriate." The situations ranged from minor, morally inconsequential ones to serious personal dilemmas in which the decision would harm someone in order to protect someone else.

Study participants were presented with the scenarios before and after 53 hours of sleep deprivation.

In general, Killgore's team found, the volunteers took a longer time to mull over the morally charged questions when they were sleep-deprived than when they were well rested. This was not the case with the more minor, non-moral scenarios.

What's more, some volunteers changed their views of what was morally acceptable after they'd been awake for two days. This was not universally true, however; volunteers who, at the beginning of the study, scored high on a measure known as "emotional intelligence" did not waver on what they found morally appropriate.

Emotional intelligence refers to a person's ability to understand his or her own emotions and those of others, and to effectively relate to other people. The findings suggest that people with "particularly well-developed emotional/social capacities" are less susceptible to the effects of sleep deprivation on moral judgment, the investigators say.

There's some evidence that facets of emotional intelligence can be developed and improved, the researchers point out. It might be worthwhile, they write, to study the effects of emotional-skills training for people who routinely face moral dilemmas under stressful conditions.