Coffee has a reputation for helping people wake up or stay awake. And yet you probably know someone who can drink coffee right up until bedtime and then go to sleep without any problem. It's a matter of how much you drink and how sensitive you are to caffeine's effects that makes this contradiction possible.
Coffee is a Stimulant
Caffeine, the best-known compound in coffee, is a stimulant that affects the brain. It is this stimulant effect that causes some people to use it to stay awake. Non-prescription medications to help you stay awake, such as No-Doz or Vivarin, are basically caffeine in pill form. It's that stimulant effect that can tell you when you've had too much coffee --- or caffeine in any form. According to the Mayo Clinic, two to four cups of coffee a day is fine for many people, but more than that can cause insomnia and nervousness.
Coffee and Staying Awake
The Harvard Women's Health Watch reports that if you want to use coffee to stay awake, you should spread out your consumption. Rather than having two or three cups in the morning, try 2 to 3 oz. every hour or so. This is particularly effective if you are sleep deprived and fighting to stay awake. And a study reported in the June 2008 issue of "Psychopharmacology" showed that caffeine significantly reduced drowsiness even in well-rested test subjects. These were women who used little or no caffeine, as the researchers wanted to assess the impact of caffeine in isolation from habitual coffee or caffeine intake.
A Contrary View
Another study from England reports that just drinking coffee on a regular basis doesn't make you more alert. Peter Rogers of Bristol University, who led the research team, reported in the June 2010 issue of "Neuropsychopharmacology" that habitual coffee users were no more alert after their morning cup of coffee than people who did not regularly consume the beverage. And people who drank coffee infrequently tended to be jittery and more anxious if they choose to imbibe on a particular day. Rogers says the caffeine used in the testing did not increase the alertness of any group --- habitual coffee fiends, occasional users, moderate imbibers --- over those non-users who received no caffeine at all. And in the test, subjects who did not normally use caffeine who developed anxiety after being given a dose, some had a genetic variant called ADORA2A, which has been linked to panic attacks.
When You're Sleep Deprived
So if you're short on sleep, you could try taking your coffee in the small, frequent dose approach suggested by Harvard University. But you probably shouldn't count on coffee to keep you alert on a regular basis, because if you use it regularly, according to Rogers, you will be less responsive to its stimulant effects.
References
- Drugs.com; No-Doz; May 2011
- Mayo Clinic; Nutrition and Healthy Eating; Caffeine: How Much is Too Much?; March 2011
- "Psychopharmacology"; Effects Of Caffeine On Alertness As Measured By Infrared Reflectance Oculography; Natalie Michael, Murray Johns, Caroline Owen, John Patterson; June 2008
- Harvard University; Coffee Health Risks: For the Moderate Drinker, Coffee is Safe, Says Harvard Women's Health Watch; August 2004
- "The Guardian"; Drinking Coffee Doesn't Make You More Alert, Caffeine Study Reveals; Jacob Aron; June 2010
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