Scientists work tirelessly to uncover the mysteries of the natural world, from the reasons people binge to the best way to wash hands. Recently it was revealed that they’ve figured out why coffee served in white mugs tastes so bitter. (The contrast between the color of coffee and a white mug makes the joe look and taste bolder.) Coffee served in clear glass mugs tastes sweeter.
So, yes, those lab rats (the people, not the animals) are obsessed with getting (and studying) that jolt of java. That study got us thinking: What other crazy things do we know about coffee thanks to science? Answer: a lot.
1. The optimal temperature
Researchers at the University of Texas at Tyler were tired of making coffee, taking a sip and burning off a layer of taste buds because the brew was scalding. So they got 300 volunteers to determine what temperature makes coffee drinkable but not mouth-burning. Those brave test subjects found that the sweet spot is 136 degrees.
2. The best time to drink coffee
We’ve been conditioned to get our caffeine fix first thing in the morning. But as Steven Miller, a psychology professor at Rosalind Franklin University in the U.S. state of Illinois, points out, early mornings are probably the worst time to drink coffee. If we pay attention to our circadian rhythms, specifically the points when our cortisol levels (responsible for the magical way we naturally feel alert) are low, we should drink coffee in the late morning (9:30 to 11:30 a.m.) and during the afternoon slump (1 to 5 p.m.).
3. The coffee-ring effect
Spill coffee on your shirt, and when it dries, the stain looks a little like a tree stump: light on the inside, dark around the edge. Scientists at the University of Pennsylvania spent more than a decade determining what causes those outer rings. The culprit: the shape of the coffee particles. Round particles form a defined outer ring, while elongated ones do not.
4. A coffee a day keeps the ringing at bay
If we’re being technical, it may be four cups of coffee a day. A study tracked the incidence of tinnitus (a constant ringing in the ear) among 65,000 U.S. women over 18 years. Those who had less than one cup of coffee a day were 15 percent more likely to have tinnitus than those who had four or more.
5. Try a coffee nap
Coffee and naps don’t seem like a natural duo: One would think that the stimulative effects of coffee should stop you from dozing off. But the boost of energy you get from a cup of coffee doesn’t happen in an instant: It takes upward of 20 minutes for the caffeine to be absorbed by your body. Researchers at Britain’s Longborough University found that drinking a cup of coffee and immediately lying down for a 15-minute nap kept sleepy volunteers more alert in a car simulator than just coffee or just a nap. We usually stick to a playlist with bumping beats to keep us awake on the road.