What is your circadian clock?
When we refer to your ‘circadian rhythm’ we are talking about the internal clock that governs your sleep-wake cycle. This ‘clock’ is controlled by the Suprachiasmatic nucleus (SCN), a collection of nerve cells located in an area of your brain known as the hypothalamus.
Image source: https://www.thepaleomom.com/the-new-science-of-sleep-wake-cycles/
The hypothalamus sits just above the point where your optic nerves cross and when these nerves signal to the hypothalamus that it is getting dark, the SCN will encourage the production of melatonin, a sleep hormone, to make you feel tired, telling your body it’s time to rest.
Your body will then pass through a number of stages whilst sleeping, with your circadian rhythm regulating your production of certain hormones and bodily functions. Your levels of melatonin usually peak at around 2-4 am and, as it approaches daylight, the SCN will trigger the release of cortisol to help you feel more awake.
Whilst your body is resting, it allows you to perform a variety of functions. Your immune system will focus on fighting any infections which is why you can sometimes be more prone to inflammation at night. Certain digestive functions may be inhibited to prevent any disruption to your sleep and you may experience a slightly higher body temperature.
Now that you have an idea about how important your circadian rhythm really is, it’s worthwhile considering what can happen when it is interrupted. When this vital body clock is disturbed it can affect many different aspects of your health. One study revealed that levels of T cells, important immune cells that attack viruses, started to drop after only one night without sleep (1).
On a regular basis, I’m sure you can imagine what this would mean for your immune system. You also have to consider that your circadian rhythm can affect your appetite, with your levels of ghrelin increasing, making you crave more sugary, carbohydrate-heavy foods the following day.
It’s even believed that SAD, or Seasonal Affective Disorder, could be caused by interruptions to your circadian rhythm, triggered by a decrease in sunlight which affects your production of serotonin and melatonin.(2).
What can affect your circadian rhythm?
Okay, so clearly your circadian rhythm is very important to your overall health and wellbeing, but how can it be negatively affected? Well a number of internal and external factors can disrupt your internal body clock, impacting the secretion of certain hormones.
One of the biggest factors you have to consider when you think about your circadian rhythm is your sleep patterns. If your body is used to resting and awakening at certain times, you are less likely to experience any disturbances. However, issues such as jet lag, shift work and even how you sleep at the weekend can have a noticeable affect.
Shift Work Disorder, for example, is particularly prevalent amongst those working night shifts and has even been considered as a probable cause of cancer (3). Although your circadian rhythm can adjust, sleeping during the day does present a challenge – the natural light will stimulate your optic nerves so it’s very rare to manage to sleep for the required 7-8 hours. You also have to consider that if your shifts rotate, your body clock will struggle to catch up and will continue to secrete melatonin during the night, affecting your work performance (4).
Known as ‘social jet lag’, more and more research is finding that sleeping in on the weekend could also be having a knock-on effect on your circadian rhythm. Most of us are guilty of enjoying a lie-in on a Sunday, but these extra hours in bed can throw off your circadian rhythm, making it more difficult for you to fall asleep on Sunday evening and consequently affecting your sleep pattern going forward.
Finally, there are certain triggers that can upset your circadian rhythms – your diet, your stress levels and even the electronic devices that you use. Too much refined sugar and caffeine, for example, will cause a spike in your blood-glucose levels, stimulating the release of cortisol during the night, effectively making it more difficult for you to remain asleep during the night. Stress is another condition that can inspire a similar reaction from your body, triggering your central nervous system.
Can you reset your circadian rhythm?
Some of the aforementioned issues disrupting your circadian rhythm are manageable, however if you do work nightshifts or travel frequently, how are you supposed to ‘retrain’ your circadian rhythm? It’s a tricky issue, however, your circadian rhythm isn’t completely inflexible and it is capable of adapting.
In the case of jet lag, it might be worthwhile trying sync your body clock with the time zone of your destination and avoiding alcohol and refined sugars before you travel. If you are involved with shift work, make sure you have a proper wake and sleep time and try to keep it consistent. Get blackout blinds and keep your bedroom immersed in darkness. Try to avoid taking naps during the day and ban devices such as your mobile phones, tablets and computers from your bedroom.
You could also consider natural remedies such as our Dormeasan. Dormeasan is prepared using extracts of Valerian and Hops and gently works to restore a normal sleep pattern. Especially useful if your sleep problems are stress-related, this remedy doesn’t have the same groggy side-effects associated with traditional sleeping pills. Simply take 30 drops 30 minutes before you go to bed and you should drift into a natural sleep cycle.
In almost every case, you really do have to consider your diet carefully – glugging down coffee to counteract drowsiness might seem like a good option but did you know it takes between 3-5 hours to eliminate half of that beverage from your system? The remaining half can linger for an even longer period of time (5).
So if you have a cup of coffee at around 4pm in the afternoon, you could still be feeling the effects at 10pm at night. If you work shifts, that 2am cuppa could spell disaster if you try going to bed at 7am.
Sugar is another catalyst to watch out for. Unfortunately, as I discussed in my blog, ‘is your lack of sleep causing you to overeat?’, sleep deprivation can stimulate hunger cravings due to fluctuating levels of hormones such as ghrelin and leptin. However, what you eat can make a real difference, so try and make more sensible decisions with your diet.
Avoid refined sugars and carbohydrates and focus on increasing your intake of fruit and veg. Certain foods do contain melatonin, so if you feel the urge to snack before bedtime, try munching on a banana or indulging in a bowl of porridge.
Originally published 14/09/17, updated 22/03/21
