Even worse, is that high levels of caffeine can create a vicious cycle, whereby you get less sleep at night, feel more tired during the day, then become more dependent on the caffeine to get you through. Unless we consciously limit ourselves to 1-2 cups a day, over time we can start reaching for a third, fourth or even fifth cup to feel the same buzz. We can become dependent on it and easily build up a tolerance to it. The other problem with caffeine is that it is addictive. Caffeine can remain in the body for up to 24 hours, so the cumulative effects over time can interfere with the whole sleep/wake cycle. Some people take longer to metabolise caffeine and may need to stop drinking coffee before midday. It takes the average person about six hours to break down just half the level of the caffeine in the body, so any caffeine consumed after about 2pm can interfere with sleep. This not only keeps us awake but it also prevents the brain from telling the body to wind down for sleep, making it harder to fall asleep and reducing your over total sleep time.

The problem with caffeine is that it blocks the effects of adenosine. Towards the evening, when adenosine levels are high, the brain sends a message to the body to start winding down for sleep. From the time we wake up in the morning a hormone is produced in the body (called adenosine) which continues to build up throughout the day. Our bodies function best with about 7-8 hours sleep and about 16-17 hours of awake time. To understand the effects of caffeine on sleep, you’ll need to first understand how the brain controls our normal sleep/wake cycle.

Drinking coffe but cant stay awake