As at the end of every semester, Reading Week forces diligent Yalies to trade rest for research. But are the late nights and intense studying actually counterproductive?

Francoise Roux, assistant professor of medicine at the Yale School of Medicine and assistant director of the Yale Center for Sleep Medicine, sat down with the News to discuss the harmful effects of stress and sleep deprivation.

Q: Describe the current thinking regarding the functions of sleep.

A: It is not really clear right now what the function of sleep is, but it seems that it helps with memory consolidation, and in body and brain tissue restoration, energy conservation and thermoregulation.

Q: What exactly qualifies someone as sleep deprived?

A: The cut-off is that most people should get eight hours of sleep a night, but at six hours you really start to see metabolic consequences.

Q: What are some of the problems associated with sleep deprivation?

A: If people are sleep deprived, they have impaired short-term memory. Sleep decreases heart rate and breathing, and lowers the release of stress hormones, such as cortisol. In the 1960s, most people slept about eight to nine hours per night. However, in 2004, the National Sleep Foundation found that more than 30 percent of adults get less than six hours of sleep per night. And 37 percent of adults experience daytime sleepiness at least a few times a week as a consequence.

Q: Are there any dangers associated with daytime sleepiness?

A: Sleepiness has been implicated in a number of mechanical and industrial accidents, such as Chernobyl. It can also affect driving ability. For driving, it is worse than being intoxicated. Additionally, it seems that sleep deprivation may have some metabolic consequences.

Q: Can you talk a little more about these metabolic consequences?

A: As we sleep less, the prevalence of obesity is increasing in the United States. Weight seems to be inversely related to sleep duration. It was found that getting less than seven hours of sleep per night was associated with weight gain, independent of a person’s physical activity.

Those who report a short sleep duration show an increased risk of diabetes. There are also studies showing that if you are sleeping for less than six hours a night, you will have a higher mortality.

Additionally, leptin, which tells you when to stop eating, is reduced, and ghrelin, which tells you when you should eat more, is increased. Sleep-deprived patients also have more cravings for carbohydrates. Sleep deprivation has been shown to increase overall appetite by 23 percent.

Q: What is the optimum amount of sleep for college-age students?

A: Nine hours. However, the National Sleep Foundation has found that the average teenager sleeps about 6.9 hours a night instead of nine.

Q: Do you often treat college students with sleep disorders?

A: Yes I do. What we see most often in teenagers is delayed sleep phase syndrome, where they go to bed too late and then can’t get up for class and find that they are tired all the time.

Q: How does stress affect sleep patterns?

A: Stress can lead to insomnia. In people who are depressed, for example, we see a decrease in REM sleep, which is the stage of sleep where we dream, and is probably involved in memory consolidation. Stress may cause people to have trouble falling asleep and staying asleep, and since we dream during REM sleep, and we have more REM sleep in the early morning hours, if people wake up early because they are stressed out, they will dream less.

Q: Do you see an increase in sleep-related problems during times of high general stress, such as around exams?

A: Yes, I have more students coming in complaining of insomnia around those times.

Q: Is there anything that students can do to counteract the harmful effects of stress on sleep?

A: Certainly. Students should learn relaxation techniques and perform good sleep hygiene. They should go to bed and get up at the same time every day and should avoid caffeine during the day, because its effects can last up to 12 hours. I also recommend that students stop drinking soda and look into cognitive behavioral therapy.