Nutrition Tips - the relationship between caffeine & sleep

By Samantha Ordonez, RDJune 30, 2021

TRIPLER ARMY MEDICAL CENTER, Honolulu – The COVID-19 pandemic has changed a lot in our society, including how we work. For several individuals, this may mean working longer hours than usual, working unusual hours such as nightshifts, staying up to provide more care to our loved ones, and having less time to sleep and recharge.

Under regular circumstances, adults need 7–9 hours of sleep each night for optimal health and well-being. A third of U.S. adults report that they usually get less than the recommended amount of sleep. Inadequate sleep is linked with many chronic diseases and conditions such as type 2 diabetes, heart disease, obesity, and depression as well as increased motor vehicle accidents and work-related injury.

Many individuals who do not get enough sleep rely on caffeinated beverages as a way to increase alertness and ability to function during the work day. It’s true that when used wisely, caffeine’s function as a stimulant can help increase alertness. However, excessive and poorly timed caffeine intake can also negatively impact sleep. Because of this, it’s important to portion size and time our doses of caffeine appropriately to maximize both alertness, sleep quantity and sleep quality.

Common caffeine sources
Common caffeine sources (Photo Credit: National Institutes of Health) VIEW ORIGINAL

Problems associated with excessive caffeine intake

Aside from making it difficult to sleep at night, consuming too much caffeine can cause disturbances to the heart, kidneys, and nervous system. According to the U.S. Substance Abuse and Mental Health Services Administration, emergency department visits increased almost 14 times between 2005 and 2011 for problems related to caffeine-containing energy drinks. Caffeine can increase urination, which can lead to dehydration. The FDA estimates that with rapid consumption of around 1200 mg of caffeine, toxic effects such as seizures can be observed.

Dietary sources of caffeine

In the U.S., most intake of caffeine comes from coffee, tea, and soda. Other dietary sources include energy drinks, chocolate, pre-workout and other supplements. For healthy, non-pregnant adults, the FDA cites 400 milligrams daily caffeine intake as an amount not generally associated with dangerous, negative effects. Some individuals may be more sensitive at lower doses, so if you are bothered by headaches, restlessness, nausea, upset stomach, jitters, or anxiety, you may want to re-evaluate how much caffeine you’re consuming.

Current FDA regulations require beverage companies to list caffeine in the ingredients list on product labels, however, there is no requirement to list the precise milligram amount of caffeine present in a product. Some companies will voluntarily add this to their product labels. See below for typical products and their caffeine contents.

Common sources of caffeine by amount
Common sources of caffeine by amount (Photo Credit: Federal Drug Administration) VIEW ORIGINAL


Caffeine takes about 30 minutes to take effect, and has a half-life of 5-6 hours. This means that it would take about 5-6 hours for half of the dose to leave the body. So a cup of coffee at lunch or afterward may keep you awake at bedtime. If you are having issues staying asleep, consider limiting the amount and/or consuming your caffeine earlier in the day.

Reducing caffeine intake safely

It is recommended to decrease your dose of caffeine gradually. Sudden drops in caffeine consumption can cause withdrawal symptoms such as headaches, fatigue, irritability, anxiety, nervousness, drowsiness, and depression.

Improving sleep

Try to recognize the stressors in your environment and that you may need more sleep or time to recover. Please see below for some tips to improve sleep, in addition to adjusting caffeine intake:

·        Use fans or air-conditioning as sleep quality improves with cooler temperatures.

·        Limit light flow through windows and doors with blackout shades.

·        Limit screen time before and around your bed.

·        Have a bedtime routine – set aside time to train your body to relax in time for sleep. Try meditating, relaxation breathing, and progressive muscle relaxation.

·        Follow a healthful diet and stay physically active.

·        Avoid alcohol, heavy meals, and nicotine for at least 2-3 hours before bed.

·        Take naps when you’re able to. Both short (15-30 minute) and long (1.5-hour) naps can increase alertness. However, know that naps are a temporary help to improve alertness, not a replacement for getting regular, adequate sleep at night.

Get help with your goals

Meeting with a dietitian can help you meet your health and nutrition goals. Tripler Army Medical Center’s Outpatient Nutrition Clinic offers one-on-one virtual or face-to-face appointments and group classes. Ask your doctor for a nutrition consult or call Tripler’s Nutrition Clinic at 808-433-4950 to learn more.


·        U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025. 9th Edition. December 2020. Available at

·        Centers for Disease Control and Prevention

·        American Heart Association

·        U.S. Food and Drug Administration