How does caffeine affect sleep?
Sleep aids are a necessary part of treatment for many people suffering from insomnia. However, sometimes it may be as simple as altering the time of caffeine consumption to treat sleep issues. Although it tastes great there are side effects of caffeine. How does caffeine affect sleep? Caffeine significantly diminishes sleep quality and quantity. It takes longer to fall asleep and there is less restorative, deep sleep. Read more to learn about the relationship between caffeine and sleep.
The average daily consumption of caffeine by adults in the US is ~300mg. The approximate amount of caffeine in 8oz of coffee is 100mg but this varies widely by different beans and brewing techniques.
How much caffeine is in coffee? To check the amount of caffeine in your favorite drinks see this link: http://www.caffeineinformer.com/the-caffeine-database.
Different amounts of caffeine per drink:
- Kcup 120mg
- Brewed coffee 163mg
- Instant coffee 57mg
- Dunkin Donuts brewed coffee 178mg
- Starbucks Grande coffee 330mg
- Coca-Cola classic 34mg
- Mountain Dew 54mg
- Monster Energy Drink 160mg
- Red Bull 80mg
- Lipton Iced Tea 48mg
- Black Tea 42mg.
Side note: Possible health benefits of coffee?
Ok, this may be slightly off the topic of caffeine’s effects on sleep but I don’t want to neglect the possible benefits of your morning coffee!
In her blog, fellow physician and coffee lover Dr. Michelle Ramirez, writes about whether coffee is a vice or a virtue. She discusses the possible health risks and benefits of coffee and includes lots of interesting coffee facts. She says:
“In general, coffee can help lower your cardiovascular risk and improve your lipid profile, decrease your risk of diabetes, help with your mood and depressive symptoms and it can prevent certain types of cancer. I didn’t mention this, but it can also help to increase your exercise output and your attention. Other studies have also suggested a reduction in development of Parkinson’s disease, risk of suicide and risk of death from all causes. Many potential benefits that reinforce drinking coffee for good health.”
Caffeine is completely absorbed within 1 hour but its stimulating effects can be evident in 15 minutes. The time it takes your body to eliminate 1/2 of the caffeine (called half-life) is on average 3-5 hours.
Some people are considered fast or slow metabolizers dependent on how fast their liver breaks it down. Half-life is affected by many factors including:
- age (older adults process caffeine slower),
- prescription medication (this article is a good review of many different medications and their effects on sleep),
- psychiatric conditions,
- smoking (causes faster metabolism),
- pregnancy (slows caffeine metabolism significantly).
The importance of half-life is that it determines how long caffeine remains in the system. On average, caffeine effects continue for 8-14 hours.
If a person says “I can fall asleep right after I drink a cup of coffee” it doesn’t mean they have an accurate perception of what is happening in their sleep. Studies have shown that even though participants denied any effects on sleep quality these detrimental effects were documented by sleep monitors. In one study, effects were tested with caffeine dosed 0, 3, and 6 hours before bedtime http://www.aasmnet.org/jcsm/ViewAbstract.aspx?pid=29198.
Caffeine was shown to reduce sleep by approximately 1 hour even when it is drank 6 hours before bedtime!
We don’t have studies documenting caffeine’s effects on sleep when consumed 9 and 12 hours prior to bed but we know that the caffeine is still in our system for 8-14 hours. Because of this, I recommend stopping drinking coffee 12 hours prior to bedtime. If this idea causes you to shudder, try at least switching to decaf (which by the way is not entirely caffeine free).
Enjoy your coffee but enjoy it in the morning!
Want more information on how to improve your sleep?
Read these posts about sleep:
I recommend these products and books to help improve your sleep and treat insomnia: