If you've ever had a coffee in the evening and struggled to sleep, you've no doubt assumed it's a simple case of too much caffeine too late in the day.
But new research suggests that coffee could be a little more complicated that we give it credit for. And it has a special and unique property that prevents us from nodding off.
Caffeine and our body clock
Turns out, caffeine doesn't only stimulate our senses and get us all revved up. It also slows down our internal clock – or body clock.
The study, published in Science Translation Medicine, discovered that coffee actually "shifts" our circadian clock – the metabolic rhythm that keeps us in sync with our environment.
The caffeine in our cuppa actually delays our clock, by up to 40 minutes! And that explains why an evening dose of the stimulating stuff keeps us up longer than usual.
Quoted by BBC News, researcher Dr John O'Neill from the Medical Research Council's Laboratory of Molecular Biology in Cambridge explains: "If you're tired and having a coffee at night to stay awake, then that is a bad idea. You'll find it harder to go to sleep and get enough sleep."
The team reached their conclusions by assessing five people over 49 days. Before going to bed, they were either:
- given a placebo
- exposed to light
- given a double shot of coffee
In the coffee drinking group, cultured cells were used to see how the caffeine affected the adenosine receptor, a key part of the body clock.
Interestingly, in this way caffeine actually plays with the rhythms of each individual cell in the body.
So if you struggle to sleep after an afternoon cup of joe, now you know why. And as Science Mag explains: "Not only do these results reinforce the common advice to avoid caffeine in the evening, but they also raise the intriguing possibility that caffeine may be useful for resetting the circadian clock to treat jet lag induced by international time zone travel."
Originally published on Oct 02, 2015
