Coffee is regarded as a transformative elixir, capable of reversing hangovers and making you sociable on a Monday morning. But what happens when the caffeine stops working? You know the feeling: It's fast approaching 3 p.m., and your fifth Starbucks of the day fails to deliver on its promise of increased energy and concentration. The effect you've come to rely on for survival is suddenly gone, and just like that, you're left to your own devices, forced to rely on a weak cup of green tea and—dare we say it—your natural energy supply for the rest of the afternoon.
Thankfully, scientists have determined the exact point at which caffeine essentially abandons you: after three nights of bad sleep. A new study from the American Academy of Sleep Medicine found that after 72 hours of poor nighttime rest, individuals were essentially immune to caffeine's normally transformative effects.
The researchers had 48 adults sleep only five hours a night for five nights in a row. Half of the participants were then given 200-milligram doses of caffeine during the day (which equates to roughly two cups of coffee) while the other half received a placebo. By the third day, the researchers found that the caffeine no longer had the same effect on the dosed half of the participants; their mood, energy levels, and cognitive abilities fell to pre-caffeinated levels, in line with the placebo group.
Unfortunately for night owls and insomniacs, it seems that nothing can replace a good night's sleep—not even a good cup of joe. Keep the three-day rule in mind when studying for a big test or preparing for an important presentation at work—your inner caffeine lover will thank you.
Have you ever experienced a caffeine fail? Tell us about it, and sip your precious morning coffee from this marbled latte mug.