We’ve known for a long time that a short afternoon nap can make a major difference to our work performance, especially if we’re involved in mental work.

Now, a new book by Harvard University sleep expert Dr Sara Mednick, Take a Nap! Change Your Life, describes the simple process of taking a nap as a “lifesaving habit”. She claims that snoozers make fewer mistakes and have boosted brainpower. One of her experiments involved one group taking a nap, another group drinking a mug of coffee (200mg of caffeine), and a control group taking a placebo.

They were then given a series of tasks, including typing and spatial skill tests. The coffee drinkers performed much worse than the placebo takers, while the nappers performed best of all. So the common assumption that coffee will keep us going through the day has probably been fed to us by the coffee industry.

Dr Mednick, a psychologist and research scientist, has accumulated a lot of evidence that a simple siesta in the afternoon is the best medicine for a happier, healthier life. People who sleep for 30 minutes at least three times a week had a 37 percent lower chance of a heart attack, according to a lead researcher from the Harvard School of Public Health.

In another study, recently published in Nature Neuroscience journal, the good doctor put 30 well-rested people through the same set of tasks four times in the course of a day, starting at 9am through to 7pm.

Performance dropped by 50 percent in those who stayed awake all day. However, the volunteers who took an afternoon nap kept up their performance throughout the day.

NASA has also made a contribution. Tests conducted by them show that astronauts who took a brief snooze doubled their alertness even if they were not tired before the nap. They also increased their work productivity by at least 13 percent.

The ideal time to nap apparently is between 1pm and 3pm which enables the most restful kind of sleep pattern for boosting performance.

I suggest you hedge your bets and take a nap now.

Knowledge is gained in pieces, but these individual pieces are not all we know. In order to understand the big picture, we put together these bits of knowledge, like pieces of a jigsaw puzzle. If we learn that A is greater than B, and that B is greater than C, we know a third fact by deduction: that A is greater than C.

Our brains demonstrate their capacity for inference by this kind of linking bits of knowledge. The ability to make logical big picture inferences from disparate pieces of information is called relational memory.

A study led by researchers at Beth Israel Deaconess Medical Center and Brigham & Women’s Hospital in Boston, MA found that this ability to link bits of directly-learned information and to make leaps of inference to construct the big picture is enhanced when we sleep.

The study involved student participants divided into three groups who learned facts about pairs of shapes they were shown. Each group was tested to see how well they were able to infer the relationship between the facts they learned about individual pairs. Group one was tested after 20 minutes, Group Two was tested after 12 hours and Group Three was tested after a full 24-hour period.

Group One, which was tested only 20 minutes after the learning period, scored the worst on understanding the interrelationship between the pairs. Approximately half of the students in Group Two slept during the 12-hour period, while the other half remained awake. All of the students in Group Three had a full night’s sleep.

Groups Two and Three showed a clear understanding of the interrelationships between the pairs of shapes.

According to senior author Matthew Walker, PhD, Director of the Sleep and Neuroimaging Laboratory at BIDMC and Assistant Professor of Psychology at Harvard Medical School (HMS), “These findings point to an important benefit [of sleep] that we had not previously considered. Sleep not only strengthens a person’s individual memories, it appears to actually knit them together and helps realize how they are associated with one another. And this may, in fact, turn out to be the primary goal of sleep: You go to bed with pieces of the memory puzzle, and awaken with the jigsaw completed.”

To Understand The Big Picture, Give It Time - And Sleep

For some people with disturbed and disrupted sleep patterns who have also suffered a mild traumatic brain injury, the trouble could be a circadian rhythm sleep disorder and not insomnia. According to the Academy of Neurology, sleep disorders can be caused by mild head injuries.

Researchers studied 42 individuals who reported insomnia following a mild traumatic brain injury. After undergoing scans, sleep studies and measurements of temperature and saliva melatonin, the study found that 36% of these patients had a circadian rhythm sleep disorder (CRSD).

Patients coming to sleep clinics due to insomnia have a CRSD rate of only 7 to 10 percent. The findings of the study indicate that misdiagnosis of CRSDs could lead to it being labeled as insomnia and the prescription of sleep medications which do nothing to normalize sleep-wake cycles. Additionally, circadian rhythm sleep disorders may be accompanied by other associated psychological and cognition problems.

The study is published in the April 3 issue of Neurology

The Academy of Neurology

Sleep deprivation can cause a multitude of health problems. Additionally it can make reflexes and reaction times slower, leading to more accidents. It affects our ability to do our work and causes us to make more mistakes. Sleep deprivation has long been used as an interrogation tactic because it lowers the resistance of the one being interrogated.

Now, the results of a study, conducted by William D.S. Killgore, PhD, and colleagues at the Walter Reed Army Institute of Research, and published in the March 1. 2007 issue of the journal SLEEP, suggest that sleep deprivation leads to difficulty in making decisions and judgments in personal moral dilemmas.

26 healthy subjects (21 men and 5 women) were tested after 53 waking hours. Sleep deprivation resulted in longer response latencies which could indicate greater difficulty in deciding upon a course of action. This finding was only true for personal moral dilemmas and not impersonal moral dilemmas or non-moral dilemmas. Following a period of sleep deprivation, there was a greater willingness to agree with solutions that violate personally held moral beliefs. This willingness, however, was moderated by emotional intelligence. Persons high in emotional intelligence were less susceptible to changes in moral judgments as a function of sleep loss.

Sleep loss causes a decline of activity in the prefrontal cortex. This area has been shown to have a prominent role in the formation of moral judgments. It is thought that sleep deprivation affects the ability to integrate emotion and cognition to guide moral judgments.

The Effects of 53 Hours of Sleep Deprivation on Moral Judgment