Coffee keeps you awake: true or false?

The idea that coffee keeps you awake is deeply entrenched, but Angela Harding wonders whether coffee really stops you falling asleep. I take it this is a topic suggestion and not a subtle hint to liven up my prose. If you do find yourself drifting off then coffee would be an effective remedy because it will, typically, keep you awake.

Coffee, or rather the caffeine it contains, is a stimulant. Many other drinks like tea, cola and any number of energy drinks will have a similar effect, depending on how much caffeine they contain. Caffeine increases alertness, reduces reaction times and — of most interest to us — promotes wakefulness.

Alright now, take a sip of Java and let’s plough on into the gritty details. Sleep is regulated by two processes in the brain which are in a kind of tug-of-war. One promotes sleep and inhibits wakefulness and the other promotes wakefulness and inhibits sleep.

Caffeine, as it turns out, manipulates both of these, keeping you awake and stopping you from sleeping. Some people are extremely sensitive to caffeine and others — probably those who are habituated through heavy and constant use — aren’t very sensitive at all. That’s probably why people like Angela are a bit unsure about whether coffee’s reputed effects are real: for some people they aren’t.

Incidentally, this is a good place to remind you that while scientists have made progress on working out how we sleep they haven’t had much luck figuring out why we sleep. Not because they’ve been napping, mind you, but because sleep seems to be tied up with the fundamentals of how the brain works — and if anyone tells you they’ve figured out how the brain works, tell them they’re dreaming. Anyway, while it’s often convenient to put off sleep with a shot of espresso, remember that sleep is actually important for...well, something.

For most people coffee can help you burn the midnight oil or work through the morning after the night before. Now you know the truth, that’s one less niggling question to keep you awake at night.

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