#30 - Sleep Pt. 2 - Circadian Rhythms and Sleep Pressure

HY3RID Podcast

We are back this week with part 2 of the sleep trilogy, talking about circadian rhythm and sleep pressure; these are our biggest regulators of sleep and tiredness, and wakefulness.

In this episode you will learn:

- What your circadian rhythm is

- How your circadian rhythm helps to regulate your sleep

- What sleep pressure is

- Why caffeine makes you feel less sleepy

- Why drinking coffee late at night is a terrible idea even if you fall asleep fine

Circadian Rhythms….What do you need to know?

Circadian rhythm is essentially our bodies internal clock, located in the brain in part of the hypothalmus called the suprachiasmatic nucleus. The reason we are interested in this daily cycle is that the onset of sleep is in part regulated by a melatonin spike in the evening, which is part of a normal circadian rhythm. Circadian rhythms differ person to person and have a genetic aspect called your chronotype influencing whether you have a preference to sleep earlier and wake earlier, or sleep later and wake later.

There are several things that impact your circadian rhythm but it's most heavily influenced and anchored light exposure.

Sleep pressure...WTF is that?

Sleep pressure is the other main regulator that generates sleep in the body. Among other products, Adenosine build up over time whilst awake as a by-product of energy production in the brain. When there is a lot of adenosine present, it binds to receptors in the brain which makes us feel drowsy, unregulated drowsiness and down regulates wakefulness. Sleep helps to remove waste products. If we get insufficient sleep, you can wake up the next day with adenosine left over from the previous day - an adenosine debt

What about caffeine?

Caffeine binds to adenosine receptor which means we don’t get that same effect of drowsiness - therefore less adenosine attaches therefore less sleepiness. However, whilst we have caffeine in our system, more adenosine is building up, meaning when the caffeine is gone you are more likely to be hit with a wave of tiredness. The half life of caffeine is roughly 6 hours, which means it takes a 6 hour period to clear half of the caffeine in your system. Caffeine not only affects onset of sleep by preventing adenosine binding, but also affects quality of sleep as you are less efficient at clearing adenosine.

A few resources we have used to help us put this together:

'Why do we sleep"by Russell Foster

Consequences of insufficient sleep- Harvard Education

"Sleep is your superpower."- Matt Walker

"Why We Sleep."Matt Walker - This book we would highly recommend.

"Chronic Artificial Blue-Enriched White Light Is an Effective Countermeasure to Delayed Circadian Phase and Neurobehavioral Decrements" - Raymond P. Najjar, Luzian Wolf, Jacques Taillard, Luc J. M. Schlangen, Alex Salam, Christian Cajochen , Claude Gronfier - Published July 2014