Caffeine and Your Sleep, or Lack Thereof

            It’s 5 A.M., and your alarm clock goes off.  You groggily wipe your eyes and slide out of the bed, using the least amount of effort possible.  Not even a shower will wake you up today.  But then, you smell the coffee brewing in your pot; instantly you start to feel more awake, even before the hot, bitter liquid reaches your lips.  As soon as it does, you are ready to take on the day and get work.

Over 60% of Americans drink coffee every day.  Most use it to wake themselves up in the morning.  Some habitual drinkers will drink it throughout the entire day, spreading into the late evening hours.  To these users, the caffeine seems to have little effect on their sleep habits.  However, researchers at University of Colorado and the Medical Research Council Laboratory of Molecular Biology in the UK have discovered just why most people seem to struggle to sleep after ingesting large amounts of coffee at night.

The first study, published in Science Translational Medicine, invited five people into the lab to observe their circadian rhythms, the biological clocks found in many cells which trigger different behavioral patterns such as feeding and sleeping.  It is well known that circadian clocks can be changed, or entrained, by light and dark periods.  People become sleepy at night because the sun goes down, causing the circadian clocks to trigger the releases of melatonin.  The participants in this study were restricted from any external light and there were no clocks in the room to tell them the time.  Some participants were placed in a room with bright lighting and others dim lighting.  These scientists found that drinking the equivalent of a double espresso roughly three hours before going to bed can delay the clock’s effects by up to an hour, disregarding any external clock regulation such as outside light.  It does this by delaying the release of melatonin in the brain.  The effect of delaying melatonin release by caffeine can shift the circadian clock back almost double the amount that bright light can.

To further prove the results, the researchers in the UK applied caffeine directly to human clock cells in the lab and studied the effects.  They discovered that caffeine acted on adenosine receptors which increased levels of cyclic adenosine monophosphate, or cAMP, which has already been known to play an important role in the functioning of clock cells.

Understanding the malfunctions of a system can lead to a better understanding of how the system works in general.  Both of these findings can help doctors and neuroscientists, such as Dr. David Cavanaugh at Loyola University Chicago, better understand the circadian rhythm system.  In his research, Dr. Cavanaugh is seeking to establish the pathway these clocks take in the brain to regulate behaviors.  By studying Drosophilia flies’ circadian rhythms, he hopes to find cells that play a part in the output of the clock cells.  He hopes to do this by genetically mutating flies and observing their activity patterns, which can lead him to determine which population of cells are involved in the system.  He also manipulates the external cues, such as light or temperature regulation, to view these effects on the circadian rhythm.

Any research into the circadian rhythm could potentially help the millions of people who suffer from insomnia or other sleep disorders.  It can also potentially help understand a multitude of other behavioral patterns that are poorly understood.  For now, the best idea would be to put down the coffee early in the afternoon and rest up before your next busy day.

References:

Brazier, Yvette. "How an Evening Coffee Can Disrupt Our Body Clock." Medical News Today. MediLexicon International, 17 Sept. 2015. Web. 4 Oct. 2015. 
http://www.medicalnewstoday.com/articles/299638.php

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