Why does caffeine make me sleepy?

Coffee is traditionally thought of as a pick-me-up, but many people find that it can actually make them feel tired. Caffeine seems to affect people in different ways, but overall there are 3 main reasons this happens.

1 – It messes with your adrenal glands

Caffeine stimulates the adrenal glands to release adrenalin, the ‘flight or fight’ hormone that prepares the body to react to a threat. It increases your heart and breathing rates, dilates the pupils and increases blood flow to the muscles. Ideally this adrenalin release happens only very occasionally during times of great physical stress.

However, when we consume excessive amounts of caffeine we promote a sustained adrenalin response, which exhausts the adrenal glands. As a result, these glands are unable to produce even the small amounts of adrenalin required to help us maintain focus and concentration, which in turn creates feelings of physical fatigue and malaise.

2 – It messes with your insulin

A secondary effect of caffeine consumption is that it can dampen the sensitivity of insulin. This hormone is involved in detecting sugar in the bloodstream and ensuring its uptake for energy production. If insulin is not working properly, we have less sugar available for energy and will feel tired.

3 – It messes up your sleep

Finally, caffeine consumption – especially at night – can reduce the amount of slow-wave sleep we get, which we need to be properly rested and rejuvenated. A consistent lack of this deep sleep will definitely contribute to feelings of fatigue.

A combination of some or all of these three physical effects of caffeine on the body can give you a recipe for fatigue.


  1. some dude says:

    These are all reasons why caffeine will make you sleepy over the long term. If I have coffee after not having had any caffeine for months, it still makes me sleepy.

  2. What the hell do you know, website.
    Caffeine was given to the Incas by the Anunnaki.
    It was given to human kind for the purpose of dis-functioning our psychic,sixth sense that we can use to WARN each other about the alien takeover.

  3. Some types of coffee makes me sleep.
    Others don’t.
    Maybe my threshold has increased and thats why only strong coffee works on me

  4. Two cups of Coffee and sitting down reading the Sunday NY Times and I’m asleep. During the week it is not so bad as I am active. At night a glass of wine or coffee is a sleep enhancer only after coffee I don’t wake up at 3-4 AM. I truly believe caffeine has an opposite effect on some us. Can’t stop. Hate that headache. Melattonin is not as good at inducing sleep as one cup of coffee. Go figure!

  5. Evangeline says:

    Yeah, I started out being just sleepy to coffee but (rightly) guessed it was years of programming since I’d always have a warm glass of milk before going to bed as a kid. So for exam periods I switched to NoDoz (but didn’t really like them because they remind me too much that I’m self medicating myself) and recently discovered V as my new fav stimulant – but it all when to hell. No less than a week into my new V regime, I found out that it had stopped working. I thought I’d overstimulated my adrenals so gave it a rest but when I came back to it for exam period this year the caffeine still put me right to sleep – all I had to do was have a can and half an hour later I’d be struggling to keep my eyes open (learnt not to test that again the hard way during an exam). So now it’s not just coffee, but all caffeine – I just lost one of my main supplies of essential nutrients as a uni student, fml.

  6. Coffee makes me all doped up and relaxed. I sure as hell don’t feel “sleepy” or “tired” or “fatigued” . Just overly relaxed. It’s like I’m so concentrated in my purpose that I do everything in slow motion. I kinda wish I was cracked up on it instead. That way I could get more work done quicker. Instead of this slow motion stasis.

    And to the annunaki preacher up there.. Good for you… Loon.

    Morpheus out.

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