Caffeine, Sleep and Adenosine
by Brandon Greco
Sleep has become the most talked about topic in the last 12 months with more and more coaches and ‘specialists’ jumping on the bandwagon of how it is the greatest tool in our toolbox to increase performance via a recovery perspective. And it is, sleep is where our bodies repair and recuperate after day’s training. And while that it is true, I believe we are still falling short within the fitness industry, especially powerlifting, with a heavy reliance on caffeinated beverages/pills (i.e., coffee, pre-workouts, fat-burners and energy drinks) to pick us up and boost energy levels before a big training session.
But what affect does this have on our ability to sleep and thus recover after big sessions?
Well let’s take a look below on an important factor in sleep, Adenosine.
WHAT IS ADENOSINE?
Adenosine is a xanthine chemical, naturally occurring within the body and is produced via the breakdown of our cell’s battery/power cell Adenosine Triphosphate (ATP).
Adenosine has many biochemical functions within the body and is one of many neurotransmitters and neuromodulators that affects sleep behaviour, specifically the initiation of sleep.
HOW DOES IT WORK?
Adenosine acts as an inhibitory neurotransmitter, simply put, it acts to suppress the central nervous system (CNS) and inhibits many processes associated with wakefulness. Adenosine levels in the brain rise each hour of the day during long periods of being awake and increase with heavy brain stimulation which consumes a large amount of ATP.
Adenosine binds to specific receptors in our brain to promote signals in our brain telling us it is time for sleep.
Therefore, adenosine is believed to be responsible for the increase in ‘sleepiness’ as the day goes on building up in specific areas of the brain like the reticular activating system (RAS) in the brainstem.
HOW DOES CAFFEINE AFFECT ADENOSINE?
Caffeine is a xanthine chemical like adenosine but works opposite. Caffeine has been shown to promote wakefulness, decrease fatigue, improve memory but by increasing wakefulness it impacts our sleep behaviour.
Caffeine has a similar chemical structure to adenosine, which allows its binds to the same receptors as adenosine thus blocking its ability to bind and promote ‘sleepiness’ within our brain.
Caffeine’s stimulatory effects are noticeable within 30-45minutes of intake but has a half-life of 5hrs. **Half-life refers to the time required for a substance’s concentration within the body to decrease by half. I.e., if you consume 200mg of caffeine, in 5 hours you’ll still have 100mg floating around.
Furthermore, it can take up to 10hrs for caffeine to still be floating around that body with an average time of 7-8hrs.
Our body thrives on sleep routine and consistency, so that high stim pre-workout, Monster Energy Drink or double shot espresso you’re having at 4/5pm before you train is still hanging around your body until 12/1am and affecting your brains ability to tell you to go to sleep.
The advice I can give is limit the intake the caffeine intake to before midday, have a strong coffee no later than 12pm (based off a sleep time around 9pm) it will still be there by the time you train then look to increase ‘hype’ and intensity via other avenues and allow your recovery to be optimal.