Napping Makes You Smarter

Two studies from Harvard show that napping make you smarter. I learned this for the first time when I was in the 7th grade. I would be in school from 8 AM to 3PM, go to work in the afternoon, and then come home at 6PM, eat supper and try to study and learn nothing. I would spend more time lying in bed thinking about studying than actually studying. So, in the seventh grade at age 12, I started a lifetime habit of sleeping every afternoon, even if I think that I don't need to sleep. I find that after just 30 to 60 minutes of sleep, I can think more clearly and do more work. If I don't sleep, I cannot write or think clearly.

Matthew Walker's study supports what I learned almost 60 year ago. He taught people to type a long list of words on a computer. He showed that those who were trained at night and were tested after a long night's sleep did far better than those who were trained in the morning and tested 12 hours later without sleeping. Thus, those who were tested after a night's sleep did much better than those who were tested after 12 hours being awake.

In the second study, Sara Mednick reported that she compared a person's ability to learn after no sleep, a 30-minute nap, or a 60 minute nap. Those who had a 30-minute nap did better than those who didn't nap, while those who took a 60-minute nap did far better than those who took only a 30-minute nap. When you start a nap, your eyes are kept still, called non-rapid-eye-movement sleep. You drop down from stage one sleep into a deeper stage two, then a deeper stage three, and then your eyes start to move rapidly back and forth. This is called Rapid Eye Movement sleep, also know as REM sleep. You learn best if you wake up right after non-rapid-eye-movement sleep (stage 2). And you get more non rapid eye movement sleep (stage 2) in a 60-minute nap than a 30-minute nap.

If you feel tired most afternoons, you are normal. In many parts of the world it is traditional to take an afternoon nap or siesta. Studies of office workers and school children show that people work best in the early morning. As the morning progresses, they lose their ability to concentrate, go out to lunch and function way below their capacity for the rest of the day. A study from the University of Pennsylvania Hospital shows that pilots, who sleep just 20 minutes during flights while their copilots take over, are more alert, attentive and responsive than those who don't nap.

It gets worse as you age. Older people fall asleep while you talk to them in the afternoon. An article in the medical journal, SLEEP, shows that a regular afternoon nap can help older people remain awake afternoon and evenings. They took a planned nap for 90 minutes between 1:30 and 3:00 in the afternoon. They were hooked up to special machines that showed that most slept for about one of the one and a half hours they lay in bed. These people had a remarkable improvement in their alertness in the afternoon and evening. They did not sleep as deeply at night and did awake a little earlier in the morning, but felt that the gain in alertness afternoons and evenings was far more important than this slight loss of sleep at night. Their sleep cycles however remained unchanged, so they still went to bed at their usual times.

Tiredness is a signal that your brain needs a rest. If you suffer from afternoon tiredness, find a quiet place to lie down during your lunch hour and take a nap. There is no data to support exercising when you feel tired because exercise does not perk you up. Recommendations to eat protein-rich foods and avoid carbohydrate ones are not based on solid data. Eating does not prevent afternoon tiredness and the drop in mental and physical performance. The only effective treatment for tiredness is rest. Set a radio to wake you to music, rather than a harsh sound that will jolt you, and expect to be far more productive than you were when you struggled to get through the afternoon and evenings without napping. Journal references; free fitness and health newsletter

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Fasting Triglycerides Test for Heart Attack Risk Unreliable

For more than 50 years doctors have used fasting blood triglyceride levels to predict a future heart attack, but now two studies in the Journal of the American Medical Association show that non-fasting blood triglyceride levels are far more dependable (July 18, 2007). When your blood sugar rises too high after eating, your pancreas releases huge amounts of insulin. Insulin converts sugar to triglycerides. Triglycerides are therefore a marker for a high blood sugar levels that damage arteries to cause heart attacks. More than 75 percent of diabetics die of heart disease.

Many people have normal blood sugar and triglyceride levels after an overnight fast, but have their blood sugar levels rise too high after eating and therefore have a high rise in triglycerides only after eating. This means that having normal triglycerides after fasting does not rule out high risk for a heart attack. High triglycerides after eating shows that you have high blood sugar levels and should restrict foods and beverages made with sugar, flour or other refined carbohydrates, the foods that cause the highest rise in blood sugar.

You can tell if you are at high risk for diabetes if you store fat primarily in your belly. Pinch your belly; if you can pinch an inch, you are at increased risk and should get a blood test called HBA1C. Having high blood levels of triglycerides and low levels of the good HDL cholesterol that helps prevent heart attacks also increases your risk for diabetes. When you eat sugar or flour, your blood sugar rises too high. This causes your pancreas to release insulin that converts sugar to triglycerides, which are poured into your bloodstream. Then the good HDL cholesterol tries to remove triglycerides by carrying them back into the liver, so having high blood levels of triglycerides and low blood levels of the good HDL cholesterol are both individual risk factors for diabetes. More on pre-diabetes; more on insulin resistance

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Muscle Sugar More Important Than Fluid for Endurance

How fast you can move and how long you can exercise intensely depends on the amount of sugar (glycogen) stored in your muscles. The same rule applies in all sports: when muscles run out of their stored sugar supply, they require more oxygen and you have to slow down.

Fluid is less important than muscle sugar because dehydration will not cause you to slow down until your blood volume is reduced. As you lose fluid from sweating, interstitial fluid stored around cells is released into the blood to maintain blood volume. When you compete is sports at a very high intensity, your muscles run out for stored sugar long before your blood volume is reduced, and you slow down from lack of muscle sugar before you slow down from reduced blood volume (Sports Medicine, April- May 2007).

Fuel for muscles comes from sugar and fat stored in muscles, sugar and fat in the bloodstream and, to a lesser degree, protein. When you start to exercise intensely, more than 50 percent of your energy comes from sugar stored in muscles. Two hours later, most of the sugar stored in muscles is used up and less than 10 percent of energy comes from that source. If you do not supply extra sugar during exercise so that your muscles will use less of their stored sugar, muscles run out of glycogen and your performance will suffer. More on hyponatremia

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Low vitamin D prevents insulin response; sunlight may not be enough

A recent study from the University of Wisconsin Osteoporosis Clinical Research Program in Madison, showed that some people have very low levels of vitamin D in spite of getting a lot of sunlight where they live in sun-drenched Hawaii (Journal of Clinical Endocrinology & Metabolism, June 2007).
The 93 participants in the study averaged 22.4 hours per week outside without sun screen. In spite of abundant sun exposure, 51 percent had low vitamin D levels.

Many people think of vitamin D as the vitamin that helps to prevent rickets, a disease characterized by weak bones that break easily. However, vitamin D does much more than that. It is necessary for your immune system to search out and destroy invading bacteria, viruses and even cancer cells. Recent studies show that lack of vitamin D prevents your body from responding to insulin adequately. The Third National Health and Nutrition Examination Survey shows that having low levels of vitamin D increases risk for high blood pressure, obesity, diabetes and having high blood levels of triglycerides (Archives of Internal Medicine, Volume 167, 2007). Researchers at Tufts University in Massachusetts showed that obesity increases a person's chances of having low vitamin D levels (Journal of Clinical Endocrinology & Metabolism, May 2007). A possible explanation is that fat sops up the available vitamin D so that it is not readily available to be used by the body.

Most people do not get adequate amounts of vitamin D from the food that they eat. They must depend on sunlight. People with dark skin require more sunlight to meet their needs for that vitamin, which could explain the increased risk for diabetes in dark-skinned people who live far from the equator. Calcium blocks the activation of vitamin D so people who take calcium supplements need to get extra sunlight or take vitamin D supplements. The large amount of calcium in milk can lower vitamin D levels even when the milk is fortified with the vitamin.

Vitamin D can be made in the skin when it is exposed to ultraviolet light from the sun. Then the liver converts vitamin D to an active hormone form called 25 hydroxy vitamin D. Then your kidneys convert this hormone to a more active di-hydroxy vitamin D. So you get that vitamin from your skin, liver and kidneys, and lack of sunlight and liver or kidney diseases can cause a deficiency. Now we learn that some people can be deficient even with adequate sunlight exposure and normal kidneys and livers. The only way to find if you are deficient of vitamin D is to get a blood test called 1,25 diyhxdroxy-vitamin D.

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Recover Faster From Exercise with Protein AND Carbs

A study from James Madison University shows that runners recover faster when they take in large amounts of protein, carbohydrates and antioxidants after their workouts (International Journal of Sport Nutrition and Exercise Metabolism, Volume 17, 2007). Athletes train by taking a workout hard enough to damage their muscles, feeling sore on the next day, and then going easy for as many days as it takes for the soreness to lessen or disappear. The sooner they recover from their hard workouts, the sooner they can take another hard workout and the stronger they will be.

Muscles are made primarily from protein building blocks called amino acids. Muscles heal from a hard workout when amino acids and other nutrients travel from your bloodstream into the muscles. Eating any food, particularly foods with plenty of protein, immediately after you finish your workout helps your muscles heal faster so you can do more work. The sooner you eat after you finish your hard workout, the quicker you will recover.

This study confirms many others that show that taking carbohydrates and proteins immediately after exercise hastens muscle healing and gets rid of the soreness faster. The defect in this study is that the authors fed a drink that combines protein, carbohydrate and antioxidant vitamins. They concluded that you need all three components to recover faster, and that a drink is superior to food. However, other studies show that you can get the same benefit from a wide variety of foods that are rich in protein and carbohydrates, and that these foods would be so rich in antioxidants and other nutrients that it would not be necessary to take any supplements. More

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Great News for Older Athletes: Marathon Times Do Not Drop Before Fifty

You should be able to compete effectively in sports that require endurance well into your later years. Researchers at the German Sports University in Cologne, Germany analyzed competitive marathon times and showed that trained men and women did not have a significant drop in their race times until they reached their fiftieth birthdays (International Journal of Sports Medicine, Volume 28, 2007). Average marathon and half-marathon times were virtually identical for age groups from 20 to 49 years. Furthermore, the drop in performance for the 50- to 69-year-old subjects was only in the range of 2.6 percent to 4.4 percent for each decade. As expected, women's times for each age group were slower than the men's times by about 10 percent for the marathon and 13 percent for the half-marathon.

These results show that most older athletes are able to maintain a high degree of physical fitness and suggest that most infirmity with aging is caused by lack of exercise, rather than just by the passage of years. If you exercise regularly, expect to be able to be stronger, faster and better coordinated than your peers who do not exercise. More on recovery times in older exercisers; fitness newsletter

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Skin Cancer Risk Linked to Diet, Not Just Sun Exposure

There are three common types of skin cancers: basal cell, squamous cell and melanoma. Basal cell skin cancers rarely spread and almost never kill; squamous cell cancers can spread and rarely kill; and melanomas often spread and have a significant mortality rate. Basal cell and squamous cell cancers are believed to be caused by excessive sunlight exposure, while melanomas are often linked to sunburns. Researchers have wondered whether other factors than sun exposure increase risk for developing these cancers.

A study from Australia shows that people who eat a diet rich in meat and other fatty foods, and low in vegetables and fruits, are at significantly increased risk for developing squamous cell cancer (American Journal of Clinical Nutrition, May 2007). This study shows that diet has little or no association with basal cell skin cancers. While nobody really knows how diet may increase risk for squamous cell skin cancers, the most likely explanation is that a diet high in meat and fat may impair your body's immunity so that your antibodies and cells are not able to search out and kill cancer cells. Fruits and vegetables are rich in phytochemicals that help to strengthen your immunity, so these foods may lower cancer risk. More on phytochemicals

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