Night Owls and Dietary Habits

In the online edition of the journal Obesity is a study about late night eating habits. Psychologists studied 51 people, 23 late sleepers (average bedtime 3:45 a.m.) and 28 normal sleepers (average bedtime 12:30 a.m.). Study participants recorded their eating and sleeping in logs and had objective sleep measurements with wrist actigraphy.

Late sleepers ate 248 more calories per day, ate twice as much fast food, ate half as many fruits and vegetables, and drank more full-caloire soda than the participants with normal sleep times. The late sleeepers consumed the extra calories during dinner and later in the evening when everyone else was asleep. Left unchecked, this amount of extra calories could lead to a 2 pound weight gain per month!

The study researchers don't know if the late sleepers consume the extra calories beacuse they prefer more high-calorie foods or because there are less healthful options late at night. It could also be that there is a circadian effect, meaning that staying awake later than normal could lead to hormone changes that affect metabolism and appetite. This, in part, could explain the fact that people who work third shift have increase risk of obesity, cardiovascular, and gastrointestinal disorders.

Poor Sleep, Insulin Resistance, and Diabetes

Diabetics who have difficulty controlling their blood glucose levels have a greater risk of complications, reduced quality of life, and reduced life expectancy. Researchers studied the association of sleep quality in diabetics. Results were published in the online version of the 3-16-11 edition of Diabetes Care.

Sleep duration and quality were estimated from 6 days of wrist actigraphy, a home sleep-measuring device worn on the wrist. Insomnia was defined as self-reported difficulty falling asleep or waking up in the night three or more times per week plus average sleep efficiency of <80% based on actigraphy.

The results showed no association between sleep measures and fasting glucose, insulin levels, or insulin resistance in the 115 subjects without diabetes. In the 40 subjects with diabetes, insomnia was associated with a 23% higher fasting glucose level, a 48% higher fasting insulin level, and an 82% higher amount of insulin resistance.

This suggests that diabetics with insomnia could have a more difficult time controlling their diabetes. The next step is to see if improving sleep quality will improve long term outcomes and quality of life for diabetics.

Obstructive Sleep Apnea, Truckers, and the FMCSA

There is an effort by the Federal Motor Carrier Safety Administration (FMCSA) to comprehensively revise the agency's rules aimed at making it harder for unfit drivers to either get medical clearance or evade detection. One area the agency is targeting is obstructive sleep apnea (OSA). During this upcoming August, the FMCSA will ask the medical review board (MRB), made up of a panel of physician advisors, on how it should proceed.

Since 2008, the MRB has supported stricter regulatory standards for OSA, by stating that all drives should be screened for OSA. The MRB recommended that a driver with a body-mass index (BMI) of 30 or more should not be allowed certification until that driver has had a sleep study. The MRB said that a diagnosis of OSA should not necessarily bar a driver from certification, but that certification should be conditioned on the OSA severity, its impact on driver's sleepiness, and whether the driver is getting treatment. It also recommended criteria for denying medical certification, including a crash associated with falling asleep at the wheel and failing to comply with prescribed OSA treatment.

Currently, there is confusion in the medical community about OSA because the MRB made the above recommendations in 2008 but the FMCSA has not made them into rules yet. Some examiners have adopted the MRB recommendations as requirements, while others are awaiting for more guidance from the FMCSA. Perhaps we will get that this summer.

Men's Thoughts, Sex, Sleep, and Food

There was a study done to see if the urban legend that men think about sex once every seven seconds is true. Psychologists asked 163 college women and 120 college men to carry around small tally counters, and asked them to record each time they thought about food, sleep, or sex. On average , the men had sexual thoughts slightly more than once each waking hour and women about half that. But the men had thoughts about food and sleep about as often as sexual thoughts.

The psychologists theorized that men could be more aware then women of their own physical state at any given time, or that men are more comfortable recording such thoughts than women. In the women who reported they care more about what others thought about them, were less likely to report food or sexual thoughts - perhaps because of the social stigma of food and sex with females. Women were equally as likely to report sleep-related thoughts, perhaps because there is no stigma with sleeping.

Sleep-Deprived Brains Turn Themselves Off

Researchers in Wisconsin and Italy discovered that when rats were kept awake four hours past their usual bedtime, parts of their brains began to turn themselves off, neuron by neuron, even though the rat was still awake. The shutdown of the neurons was random, but progressive - this was what the researchers thought was responsible for the rats decreasing performance on a task where they had to find a sugar pellet. Researchers said there is no reason to believe this progressive shutdown does not occur in humans.

This finding is important because it means that there could be performance decrements when tired or sleepy, and these decrements could occur before the person even realizes it. There are implications for drivers and those who operate heavy machinery who happen to be sleep-deprived. It could also affect test-taking in sleep-deprived students.

Sleep Duration, Sleep Quality, and Cardiovascular Disease Risk

I just came across a blurb about the MORGEN Study (Monitoring Project on Risk Factors and Chronic Diseases in the Netherlands) which explores the associations of sleep duration and sleep quality with cardiovascular disease (CVD) and coronary heart disease (CHD).

Researchers surveyed more than 20,000 men and women ages 20 to 65 years old about their sleep quality and quantity. The followed them for 10 - 15 years and recorded morbidity and causes of death. Sleep quality was assessed by asking "Do you usually rise feeling rested?"

The results showed that people who slept less than 6 hours per night had a 15% higher risk of incident CVD and 23% higher risk of CHD, compared to people with normal sleep duration (7-8 hours per night). On its own, there was no increased risk of CVD in patients with normal sleep duration, but reduced sleep quality. However, in those with poor quality sleep and short sleep duration, there was a 65% increase risk of CVD and an 85% increase risk of CHD when compared to people who had good quality sleep and slept normal duration. Interstingly, there was no correlation between sleeping longer than 8 hours and CVD, a finding which contradicts other studies.

There is no mention of obstructive sleep apnea or obesity, which could affect sleep duration, sleep quality, and increase CVD and CHD risk.

The bottom line is that if you are sleeping less than six hours per night, and feel your sleep is poor quality, talk to your doctor. Your heart health could be in jeopardy.

Short Sleepers

There is an article in the Wall Street Journal about people who need less than six hours of sleep per night - a.k.a short sleepers. Short sleepers are less common than most people think. In fact, the article quotes a famous sleep psychiatrist, Dan Buysse, who says that there only 5-6 true short sleepers for every 100 people that make such claims. People who tolerate six hours or less of sleep per night for the work week are not what we call short sleepers. If you can sleep longer on the weekend, than you are not a short sleeper. You are sleep-depriving yourself during the work week and catching up on lost sleep on the weekends. Short sleepers sleep < 6 hours seven days a week.

We don't know why some people are short sleepers. It can start in childhood and can run in families. There is no way a person can teach themselves to be a short sleeper either.

Short sleepers tend to be more energetic, outgoing, optimistic, and ambitious. Their metabolism tends to be higher than regular sleepers. The article in the WSJ thought this was confusing, since sleep deprivation is linked to obesity. However, it could be argued that true short sleepers are not sleep-deprived. Finally, short sleepers tend to have higher tolerance for physical pain and psychological setbacks.

Currently, researchers are attempting to find out the genetics behind short sleepers. This could have applicability in our fast-paced modern lifestyle. In the mean time, get some sleep...enough sleep.