When it reaches a certain level, you’ll feel drowsy and get the urge to sleep.

It acts as a neurotransmitter, telling the brain when to rest, and depressing the central nervous system. That sleepiness you feel is all down to adenosine, a chemical that naturally builds up in your body all the time you’re awake. If you’ve been finding caffeine hasn’t been working for you, you may have been reaching for more of it each day, which has been keeping you up later, building up your sleep debt, and making you feel even more tired. In fact, one study found after three nights of five hours of sleep a night, caffeine no longer boosted alertness or performance.Įverything from your focus to your mental health to your physical performance will take a hit when you’re suffering from sleep deprivation.

If you’ve got a lot of sleep debt, no amount of caffeine is going to make you feel more awake. It’s measured against your sleep need, the genetically determined amount of sleep you need each night. Sleep debt is how much sleep you owe your body over the last 14 nights. The RISE app can work out how much sleep debt you have.

Doesnt affect me