Have you ever gotten into thinking about how your body knows when it is time to be awake and when it is time to sleep? Ok maybe you haven’t but I’ll continue anyway, as it’s an important concept to understand if you would like to optimise your sleep, and therefore, your health and performance.
Life on Earth has evolved over billions of years, and one of the key evolutionary developments which has been vitally important to sustaining and enhancing life has been the development of the Circadian Rhythm.It is certainly a term you may have heard of but let me explain a little more.Circadian Rhythm refers to the biological rhythm(s) which our bodies undertake to adapt to the biological day. This allows our bodies to synchronise to the daily rotation of the Earth and to its orbit around the sun. Your Circadian Rhythm is the orchestrator for all your bodily processes, hormonal release, cravings and urges that you go through each day. Dictating when you’re alert, when you want to sleep, when you are hungry, when you recovery, when you are at your most potent physically and mentally…. It really does pull all of your strings.
National Institute of the General Medical Sciences definition of Circadian Rhythm "Physical, mental and behavioural changes that follow a 24-hour cycle”
Circadian Rhythms are driven by Zeitgbers (meaning, time-givers),which signal to your body what time it is and provoking your body to respond with an appropriate behaviour. For example, the sun rises in the morning, light penetrates your eye-lips and is perceived by your brain…. You wake up. Forgive the over simplification, but hopefully you get the gist.
Understanding what your Circadian Rhythm is, and how it responds to differing stimulus’ can be the basis of understanding why and how you need to sleep and how you can manipulate your body to be more alert at times when you’ve not been able to acquire enough rest, which let’s face it, happens to us all on at least a semi-regular basis.
Another interesting fundamental to understand when it comes to Circadian Rhythms is the fact that this driver of wakefulness and sleepiness undulates during the day. In figure 1 you can see how this occurs, with the line representing your Circadian Rhythm and how it dips and gives you a greater urge to sleep, and also when it rises to give you greater alertness and potentially a burst of energy. Interesting to note is that there is a dip during the early-mid afternoon, this is associated with the mid-afternoon slump which we've all fallen victim to on occasion
I’m writing this at the beginning of the winter months in the UK, and on this specific day the sun rose at 7.22am and will begin to set at 4.08pm. As I’m sure you agree, this is a relatively short day and therefore we have a significantly reduced chance to expose ourself to our biggest Zeitgber, the sun. It’s no coincidence that at this time of year we tend to feel lethargic, but this is not reflected in a greater need for sleep. This is further compounded by the greater number of us working from home, with people being outside even less as they no longer commute to work like they did pre-covid.
Knowing this can be very useful when you are trying to understand why you may feel a certain way at a certain point of the day and that one of the most useful hacks for feeling more alert is get yourself outside and get a good blast of sunlight. Try it, expose yourself to your bodies greatest time-giver. You might be surprised at the positive impact it will make on how you feel during the day and when you feel tired in the evening.
In short, your Circadian Rhythm is an incredibly complex system that has evolved over billions of years. Understanding it, and how to work with it will do you the World of good…. Go out, get some light in the morning and reap the rewards.
Many thanks for reading
Learn more about your Circadian Rhythm and how best to support it to enhance health and performance by keeping an eye our for Production Education, coming soon.