03/18/2010 05:12 am ET | Updated Nov 17, 2011

Sleep Tip: Be Careful With Caffeine

The older we get, the more quality sleep we need. Sleep is a holiday for the body, a time when every system has a chance to relax and repair itself. What you do with your body and brain throughout the day influences how well your body and brain sleep at night. If you put a lot of junk food and junk thoughts into your body during the day, don't expect the resulting neurochemicals to become nicer at night. The vicious cycle begins: Suboptimal sleep throws the sleep inducing neurochemicals out of whack, and this in turn leads to more suboptimal sleep. Inadequate sleep amps up the inflamatory system and causes you to store excess body fat, both of which increase your chances of getting sick and sleeping less.

One frequently-recommended tip for achieving better sleep is to cut back on caffeine, which sounds logical, but we rarely hear the reasons why. The effect of caffeine consumed during the day causes the brain and body to act like they are in a state of "perpetual stress" in the evening. People who are already tense get what I call the "carryover effect" of caffeine, and it only makes them more tense, causing them to sleep poorly at night. This makes them more anxious the next day, and the cycle gets worse. Ultimately, too much caffeine can actually zap rather than boost energy.


1. Caffeine can act as a stimulant and as a depressant. While caffeine in the appropriate doses can perk up the brain, high doses can leave you feeling depressed. (I use the word dose because caffeine is a drug.) The busy electrical activity in the brain has a sort of built-in brake that automatically slows down the thinking neurotransmitters from going too fast. Caffeine tells the brain to ignore the brake pedal and allows the neurotransmitters to speed. How much caffeine it takes to perk up the brain and how much depresses it varies considerably from person to person.

2. The caffeine effect can be addictive. As with any drug, the body habituates to caffeine, meaning it takes higher and higher doses to achieve the desired effect. At first one cup of coffee perks you up, then it takes two cups, then three, and so on. The higher the dosage, the greater the side effects. This is why it's important to take "caffeine holidays" if you are a regular java jolter, so that you can gradually lower the number of cups you drink. Lowering your dosage too fast, however, can lead to withdrawal symptoms, such as extreme fatigue, depression, headaches, and jitteriness.

3. Caffeine can be hard on the heart. There is conflicting research as to whether caffeine is heart healthy or heart harmful. My advice is to follow the science of common sense: Caffeine increases the blood level of the stress hormone adrenaline, which speeds up not only brain activity but also heart rate and can raise blood pressure. Any drug that increases the circulating levels of stress hormones can't be good for the brain or the body. So go easy.

4. Caffeine can bother the bones and upset the tummy. For some people, excess caffeine can cause excessive excretion of calcium in the urine. Also, because caffeine can increase stomach acid secretion, prime timers who already suffer from reflux or heartburn should limit caffeine or at least sip their coffee or tea slowly and not on an empty stomach.

My advice on caffeine:

• If you don't already drink caffeine-containing beverages, don't start.

• Choose decaf coffee and tea. Coffee beans are decaffeinated in two ways: They can be soaked in water to leach out the caffeine or be processed chemically. Because I generally trust nature more than chemistry labs, I go for water-processed decaf. You can decaf your own tea: Pour a cup of hot water, dip the caffeinated tea bag into the hot water for 20 to 30 seconds, then discard the water. You've just removed most of the caffeine from the tea bag but retained the flavor and flavonoids.

• If you do have caffeine-containing drinks, limit your caffeine milligrams to no more than twice your body weight. So if you weigh 100 pounds, you should have no more than 200 milligrams of caffeine a day, which is about two cups of coffee or three cups of black tea.

• Since caffeine may take as long as twelve hours to clear your system (the half-life of caffeine is about six hours), get your java jolt in the morning, if you must.

Dr. William Sears is the father of eight children and the author of over 30 books on childcare. His latest book is called Prime Time Health: A Scientifically Proven Plan for Feeling Younger and Living Longer.

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