Insufficient sleep is well known to increase the risk of cognitive and mood disturbances as well as cardiometabolic disorders.  The American Heart Association recently added to the list of key factors essential to help maintain cardiovascular health to include the recommendation for adults to aim for an average of 7-9 hours of sleep.   A crucial step in achieving adequate quality sleep involves practicing good sleep habits, also known as sleep hygiene. One of the basic tenets of sleep hygiene is avoiding caffeine before bedtime.  

Caffeine is a stimulant that, when consumed, essentially works through blocking the body's receptors to a sleep-promoting chemical known as adenosine.  Normally, adenosine levels slowly build in the body throughout the day, slowly increasing our sleep drive, and ultimately making us feel ready for sleep at night.  Under the influence of caffeine, however, adenosine's effects are suppressed which increases alertness and inhibits sleep. 

The Sleep Medicine Review Journal recently published this article taking a closer look at the relationship of caffeine on subsequent sleep in order to determine how long before bedtime caffeine should be avoided.  The results of the study showed that caffeine consumption resulted in a 7% reduction in overall sleep efficacy and a 45-minute reduction in total sleep time.  The degree of reduction in total sleep time was directly correlated to the amount of caffeine that was consumed as well as how soon it was ingested prior to bedtime.  Caffeine use also contributed to an increase in the time it took to fall asleep, and the amount of time spent awake during nocturnal arousals.  Upon further analysis, the data revealed an optimal caffeine cut-off time of just over 8 hours for a single cup of coffee to avoid sleep disruption, with earlier cut-off times necessary with higher amounts of caffeine consumption.

Roughly 20-45% of the population is estimated to be sleep deprived with failure to achieve the recommended 7-9 hours of sleep each night.  The results of this research indicate that caffeine use has a clear effect on subsequent sleep and can increase one's risk of inadequate sleep.  Therefore, to ensure sufficient good quality sleep, it is important to prioritize adherence to sleep hygiene basics and to regulate caffeine intake well before one’s intended bedtime.