Thereâs no question that a hit of caffeine will keep you up a little later at night, but the impact it has on your sleep cycle might be more than you think. I was a little surprised when I recently read the findings of a new study that focused on just that topic.
The Health Effects of That After-Dinner Coffee
More precisely, the study suggested that the equivalent of 200 milligrams (mg) of caffeine (generally what youâd find in a double espresso or larger coffee) three hours before bed can delay your internal clock that tells you when itâs time for bed and when itâs time to get up. And when you delay your circadian rhythm (your natural sleep/wake cycle), bad things can happen.
First off, you create a sleep deficit that needs to be made up over time. Secondly, you leave yourself feeling tired, groggy, and unprepared for the demands of the day. Ultimately, this can impact your decision-making abilities and greatly increase your chance for injury.
In the study, researchers noticed that subjects given caffeine three hours prior to sleep didnât have the boost in blood melatonin (the sleep hormone) until 40 minutes after those taking a placebo. This means that caffeine consumption within three hours of your bedtime can delay your circadian rhythm by 40 minutes!
Why Caffeine Affects Your Sleep Cycle
At the end of the day, blood melatonin tends to rise in humans, signaling that itâs time for bed. Comparatively, it is lowest in the morning when you wake up. There are various factors that influence its onset, predominantly exposure to light and caffeine intake.
Caffeine, the most widely used psychoactive drug in the world, can also block cell receptors that promote sleep. But I wouldnât go as far as saying caffeine is generally bad. In fact, I would say the oppositeâthat caffeine, and more specifically coffee, is healthy for you. But this is entirely dose- and time-dependent. Coffee, for example, can lower your risk of cardiovascular disease, liver disease, and type 2 diabetes and can be a great source of antioxidants. But if you want to improve your health, you must drink your coffee in the morning or afternoonâsticking far away from your bedtime.
During your next dinner party, if you feel you mustnât decline a warm drink, ask for some herbal or decaffeinated coffee or tea instead of an espresso. Alternatively, listen to your body and know when itâs time to wind down for the night to ensure you get a good nightâs sleep and keep your circadian rhythm on beat!
Sources for Todayâs Article:
âCaffeine at night delays human circadian clock,â ScienceDaily web site, September 16, 2015; http://www.sciencedaily.com/releases/2015/09/150916161833.htm.
Zhang, Y., et al., âCoffee consumption and the incidence if type-2 diabetes in men and women with normal glucose tolerance: The Strong Heart Study,â Nutrition, Metabolism and Cardiovascular Disease, doi:10.1016/j.numecd.2009.10.020.
Corrao, G., et al., âCoffee, caffeine and the risk of liver cirrhosis,â Annals of Epidemiology October 2001; 11(7): 458â65.
Wu, J., et al., âCoffee consumption and risk of coronary heart diseases: A meta-analysis of 21 prospective cohort studies,â International Journal of Cardiology, December 2009; doi:10.1016/j.ijcard.2008.06.051.