Wake up and smell the coffee – assuming you got to sleep in the first place

I’m off next week to Northern Ireland to stay with my in-laws. One of the things that always amuses me is our differences around caffeine. If I have a filter coffee after about 4pm, I don’t sleep. It may be a self-perpetuating myth, but it’s a rule of thumb that I’ve developed after many dinners in the past followed by sleepless, wide-awake nights.

In their house, however, a good filter coffee is a nightcap. (For some, it should be an espresso with a fag to help it down.)

I’d always written it off to bodily differences – I don’t process caffeine as well (ditto alcohol, as many student friends can attest – and some current colleagues still try and test…), while they process it without the same effects.

And it turns out there’s truth in that – but there’s more to it than just whether you can get to sleep after a coffee.

begin to dig: Caffeine makes us Crazy – or at least messes with our sleep is a great article on how caffeine does have an effect on our sleep, even if we get to sleep with caffeine coursing round our veins. The article itself is a summary of a paper on Caffeine and the Brain but shows the effect we can point to.

Many are the ones we already know – instinctively or through research – it can fool our systems into thinking we’re not as tired as we really are. (The article actually gives the mechanism by which it does this – I love knowing the ins and outs of stuff like this.)

Around sleep, however, there are two particular effects that I find fascinating:

  • It disrupts our deep sleep phase – where all sorts of interesting things happen. Athletes build physical function in deep sleep – with coffee in their system, not so much…
  • It doesn’t prevent the effects of sleep deprivation kicking in. This feels pretty familiar to anyone who’s pulled an all-night shift, fuelled with the murky outpourings of the office coffee machine. You’ve stayed up, felt pretty alert, but the next day you still end up functioning less and less well.

And the worse news is how long it lingers in the system.

Ugh. I like my coffee, I’m not going to go wholly caffeine-free any day now, but I may just re-look at those lattes and cappucinos in afternoon meetings…