As many as one in three older adults suffer from some form of insomnia ranging from difficulty falling asleep to waking up in the middle of the night, often because of painful ailments or other medical problems.

But some over-the-counter medications commonly used to relieve aches and pains may compound the problem (caffeine is often added to analgesics because it helps decrease pain and other aches). That’s because these top brands of pain relievers may contain more caffeine than a cup of coffee – a definite problem for someone who’s having trouble sleeping.

According to Tufts University, a study from the National Institute of Aging showed that more than 20 percent of adults using caffeine-containing medications reported having difficulty falling asleep compared to only 13 percent of those who didn’t take the medication. 

How Caffeine Works

Caffeine works by stimulating the central nervous system and increasing our heart rate. In the brain, it blocks adenosine (a sleep-promoting chemical) receptors. Normally, adenosine builds up during our waking hours until eventually, we become sleepy. Caffeine blocks this process making us more alert. Caffeine also blocks our circadian melatonin rhythms, delaying sleep if consumed close to bedtime.

The effects of caffeine are measured by its half-life, which typically lasts about 4-6 hours. Thus, the 6-hour half-life of the caffeinated beverage you consumed in the afternoon could potentially be keeping you up at night. 

How Much Caffeine is Recommended?

The Food and Drug Administration (FDA) recommended dosage/day is approximately 400 mg/day. If you have an espresso or a large cup of coffee, analgesics with caffeine, or other caffeine-containing products, this adds up fast. Take a look at the chart below.  Some of the medications have well above the milligrams of caffeine (@100 mg) found in a regular cup of coffee.  If you’re swallowing these pain relievers on an average of six-hour intervals, you could be getting as many as six cups of coffee without even realizing it. 

If you struggle with insomnia or have a difficult time falling asleep or staying asleep, this might be a sign of caffeine overuse. Look at your intake of coffee or other caffeine-containing products, and you may find a little tweaking here, or there can give you those restful zzzzzzzzzzz’s your mind and body are craving.


Cindy Maynard, Ph.D., RD, is a health psychologist, a registered dietitian, and a nationally published health and fitness writer. She is passionate about promoting health and wellness.  You can contact her at