Regardless of the form, caffeine has been widely used to help promote alertness. Popular coffee houses know how valuable that little pick-me-up can be to those struggling to wake up in the early hours of the morning or stay alert in boring meetings throughout the work day. However, we all know, if taken too late in the day, caffeine can keep us alert throughout the night.

As early as 1672, coffee has been prescribed for disorders of sleepiness. Caffeine’s main mechanism of action is through the antagonism of adenosine receptors. Endogenous adenosine levels rise with continued wakefulness and may be a fundamental part of sleep.  Exogenous adenosine promotes slow wave sleep. Xanthines, which include caffeine, block the A1 adenosine receptors, thereby inhibiting sleep.  Caffeine typically peaks 30 minutes to 1 hour after ingestion and has a half-life of 3 to 5 hours.

Caffeine, if used appropriately, can benefit those that need to be alert, including medical personnel, truck drivers, and shift workers. However, at high doses, caffeine can also cause unwanted side effects such as tremors, muscle tension, diarrhea, flushing, sweating, increased heart rate, and increased respiratory rates. High doses of caffeine can be as effective as low doses of stimulants, so some patients may prefer to get wake-promoting stimulation from a caffeinated beverage than from the pharmacy.

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The Department of Defense, along with several other government agencies, have now produced a model, called 2B-Alert, that can design a sleep/wake schedule and caffeine consumption schedule to improve alertness. The graphing tool is able to display up to 7 different sleep/wake and caffeine schedules to optimize neurobehavioral performance.

There are many advantages of this tool. It helps individuals who need to stay awake and alert predict when it is best to drink their caffeine.  It could also be used to help patients know when it might not be optimal to drink caffeine.  The disadvantages are there too, as patients may abuse this model for more time to stay awake when they should be trying to sleep.

What are your thoughts? Is this something that you would use personally or professionally? Would you encourage your patient to use this tool?

Sharon M. O’Brien, MPAS, PA-C, is a practicing physician assistant and health coach in Asheville, NC.


  1.  Ramakrishnan S, Wesensten NJ, Kamimori GH, et al. A Unified Model of Performance for Predicting the Effects of Sleep and Caffeine. Sleep. 2016;39(10):1827-1841.
  2. Wake-Promoting Medications: Efficacy and Adverse Effects. In: Kryger MH, Roth T, Dement WC. Principles and Practice of Sleep Medicine. 4th ed. Elsevier Health Sciences. 2005.