Dr. Roach: Alcohol metabolism is more complicated than a drink an hour
Dear Dr. Roach: I’ve frequently read that while alcohol might help you get to sleep, it disturbs your getting back to sleep later in the night. I believe that your body dispenses with the alcohol effects at the rate of about one drink per hour. Thus, if I have a drink at 6 p.m., another at 7 p.m., and a third at 8 p.m., I should be sober by 9 p.m. and absolutely by 10 p.m., when I go to bed and easily go to sleep. If I go to bed sober, am I still subject to some alcohol effect at 2 a.m.?
Dear A.B.: You are right that alcohol can have variable effects on sleep, and waking up after a few hours (called middle insomnia) is one of those.
You also are right that alcohol is metabolized by the body at roughly a constant amount; on average, it’s about 7 grams of alcohol per hour, which is roughly equivalent to one “drink,” but that amount of alcohol varies by the concentration and quantity. However, the situation is even more complex than you have summarized.
Alcohol isn’t absorbed instantly. The higher the concentration of alcohol, the faster it is absorbed. Food slows alcohol absorption, which is why it’s recommended not to drink on an empty stomach. It always takes some time for the alcohol to be absorbed, but if you have eaten, it will be longer.
You are likely to still have alcohol in your system at 9 p.m., having had three drinks in the three hours. The first drink wasn’t completely metabolized as soon as you started drinking, allowing blood concentration to increase, which means your liver can’t get rid of it as soon as you may think.
Depending on who you are, that “one drink per hour” rule may be very inaccurate. Although there is individual variation, women tend to metabolize alcohol less quickly, as do people of Asian descent. People who drink often, especially in large amounts, tend to be able to metabolize it more quickly. Some medications slow alcohol metabolism. All of these characteristics may change the rate of alcohol metabolism three- or even fourfold.
The effects of alcohol on the body are not gone when the alcohol is gone. Metabolic byproducts of alcohol metabolism can have important effects on the body. Also, alcohol changes the type of sleep you have; it suppresses REM sleep, and a loss of sleep quality may be as bad as a loss of quantity. These factors still might be having an effect even six hours after the last drink.
A good rule for men is not to exceed two drinks per night; women, because of their generally smaller body size, relatively smaller livers and relatively less alcohol dehydrogenase enzyme (the major metabolizer of alcohol), should not exceed one drink daily.
Dear Dr. Roach: My wife read an article that said women should not take more than 8 milligrams of zinc. Her eye doctor gave her pills containing 80 milligrams of zinc. She says she won’t take them because of the zinc amount. Is she right?
Dear J.J.N.: The recommended daily allowance of zinc for women is 8 milligrams, meaning that this dose should prevent zinc deficiency in 97 percent of people getting that amount. Amounts up to 80 milligrams are considered safe, and the AREDS study, which looked at doses of 80 milligrams, confirmed that safety. The major concern of excess zinc is that it can prevent absorption of copper, so copper supplementation should be a part of the supplement her eye doctor gave her.
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