So, if you’re sipping a coffee and feel like it’s doing nothing for you, it may just be because you’re in a natural dip in energy. But even if you’re not sleep deprived, you’ll still feel it - it’s a natural part of your biology. You’ll feel this dip in energy more strongly if you’re carrying a lot of sleep debt. We all experience natural peaks and dips in our energy levels throughout the day, with one of those dips being in the afternoon. This is the internal body clock that runs on a roughly 24-hour cycle, dictating when you feel awake and when you feel sleepy. You know that afternoon slump when you suddenly feel sluggish? That’s your circadian rhythm at play. The RISE app can tell you when your energy peaks and dips will be. The app then works out if you’re carrying any sleep debt and, if so, how much exactly. The RISE app uses your phone use behavior to calculate your sleep need, giving you a number to aim for each night. Working out how much sleep debt you have doesn’t have to be difficult. But if you haven’t been meeting your sleep need, you’ll have a lot of adenosine in your system, meaning you’ll feel the sleepiness effect of the chemical, even with caffeine in your system. And when you do sleep, adenosine is purged from your system, so you wake up feeling less sleepy, and the cycle starts again.Ĭaffeine works by temporarily blocking the adenosine receptors in your brain. 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.

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