What is circadian rhythm, and can we optimise it?

All you need to know about your body clock - and how to optimise it for health and sleep 🕒

Did you know that all our bodily systems ( in fact every single cell in our body) are controlled by an innate 24 hour clock, called the circadian rhythm?!

 While it's mostly known for its effect on sleep, the circadian rhythm actually has many other functions, controlling :

✔️digestion (releasing enzymes at usual meal times) 

✔️hormone levels (ie energy levels, growth, insulin, cortisol) 

✔️blood pressure

✔️physical strength

✔️appetite

✔️blood sugar and cholesterol levels

✔️immunity

✔️ brain health

✔️cell and DNA repair

As a result, disrupted circadian rhythms can have far reaching effects, increasing the risk of disease and even reducing life expectancy!

Our circadian rhythm is controlled by a master clock in the brain called the suprachiasmatic nucleus (SCN)

This contains genes called clock genes, which send out signals at different times of the day to regulate bodily functions

The SCN is controlled by signals from the environment (ie light, food, activity, temperature  etc), in particular blue light exposure (from natural outdoor light, and screens) . This means our environment plays a key role in both our sleep quality, and our circadian rhythm (and therefore our health!)

Our circadian rhythm makes us :

 ✔️sleepy at night (via melatonin, the sleep hormone) 

 ✔️tired mid afternoon

 ✔️hungry at meal times

 ✔️warmer in the evening and cooler overnight

Its also why we get jet lag changing time zones, why shift workers have higher risk of various health issues - and why teenagers are often night owls!

So given how important it is, what's the best way to optimise circadian rhythm?

✔️Exercise outdoors in the morning if you can - blue light levels are most intense then, and this sets the clock for the rest of the day. The SCN is particularly sensitive to blue light. This also helps regulate cortisol 

✔️Keep your room cooler at night, to allow body temperature to drop (around 18-20 degrees is ideal) 

✔️Avoid bright lights and screens 2h before bed (these suppress melatonin secretion, and reduce duration and quality of sleep ) 

✔️Avoid caffeine after 2pm, and alcohol within a few hours of bed

✔️Avoid vigorous excercise before bed, try some gentle stretching

✔️Practice time restricted eating (stop eating by 7pm at the latest, and aim to fast for ideally 14h overnight - this seems to be optimal for metabolism, weight, and blood sugars). It's also important to try eat at similar times each day, especially the first and last meals of the day, as our body ‘remembers’ this, and responds to food accordingly (which can affect weight gain, blood sugar levels, cholesterol and more)

It's simple but so effective!!