Reviewed for Accuracy by Dr Jason Ellis
Circadian rhythm definition:
any periodic variation in physiological or behavioural activity that repeats at approximately 24-hour intervals, such as the sleep–wake cycle.
Source: APA dictionary
If you’ve ever spoken about your body clock, you’ve actually referred to one of your circadian rhythms. But what exactly are these rhythms? And why should they be considered when looking to improve your approach to sleep? Here, we take a look at this important biological cycle with some tips on how to get yours in sync and achieve better sleep health.
Aside from circadian rhythms, there are three other types of biological rhythm: diurnal, ultradian and infradian.
These rhythms complete over a much shorter time period than circadian or diurnal. For example, they can refer to the lifespan of a heartbeat. They repeat in a loop throughout the day and are what keep us going all day and night.
There are numerous factors that can affect and disrupt your circadian rhythm. If you’re struggling to sleep or keep a sleep routine, it’s worth exploring the below factors and considering whether they are affecting you.
We’ve all heard about the dangers of blue light before bed. Typically, this comes in the form of screens. The lights emitted from phones, laptops and tablets trick our body into thinking it’s still daytime. This makes it more difficult to sleep. And beyond our sleep, it also impacts our mood and can cause health issues later in life. Here’s what the science journal Translational Psychiatry had to say on the matter:
“When exposure to light is mistimed or nearly constant, biological and behavioural rhythms can become desynchronized, leading to negative consequences for health. The relationship among mood disorders, light, and circadian rhythms have long been recognized.”
Shift work disorder is a risk for those whose work activity begins, or ends, outside of the standard daytime working hours of 7am to 7pm. And with the always-on nature of the 21st century, the number of people working in these industries is increasing. For bartenders in late licence bars, healthcare workers on night shifts, and countless other irregular hours workers, the body will find it difficult to differentiate between sleep time and work time. A big factor that affects shift work disorder is the production of melatonin. This hormone is what kicks in our sleep routine but it is only produced at night. For those trying to sleep in the day, a focus on your melatonin levels could be key. Read more in our guide to melatonin and sleep.
Obviously, you can’t just leave your job and take on new shifts. So, combatting shift work disorder through other means is important. Here are some tips:
If the only downside of holidays abroad is jet lag, then the downside of weekends is a phenomenon called social jet lag. In scientific circles, this term refers to how we alter our sleep cycle to account for social events. Coined by German researcher Till Roennenberg in 2006, this theory largely centres on the discrepancies between our sleep and wake routines on weekdays and weekends. Here’s how he describes social jet lag:
“We proposed SJL as a concept that describes and quantifies the chronic discrepancy between an individual’s biological clock and the social clock. As such, we envisioned SJL as a measure of circadian misalignment.”
In the study for Translational Psychology, further research was undertaken on how sleep is impacted by discrepancies between work or school and our social lives:
“A large scale epidemiological study confirmed that both sleep timing and duration are substantially challenged by work and school schedules or other social events. To align sleep and wake times with social obligations, 80% of the population uses alarm clocks on school or workdays. Early school and work schedules are particularly difficult for individuals with late chronotypes.”
Fortunately, we’re not here to advocate for missing social events. After all, socialising is important for our mental health. It’s quite simply about balance. Try to ensure you aren’t staying up late multiple times a week. If you can limit your late nights to one per weekend that should help. And on those nights where you’re getting to bed late, set your alarm for a reasonable time the next day. Try not to sleep into the afternoon as this will kick your circadian right out of sync.
It’s common knowledge that caffeinated and alcoholic drinks are bad for our sleep routine. Put simply, they’re loaded with chemicals that make it difficult for our body to nod off. But when it comes to diet and nutrition for your circadian rhythm, there is more that can be taken into account.
For example, there are plenty of foods which can help boost melatonin, a crucial hormone for sleep. Most commonly, there are plenty of foods which contain the following sleep-inducing minerals and vitamins:
Here’s a starter pack for what to include in your diet to help boost melatonin and kick-start your circadian rhythm. Hopefully, you’ll already have incorporated some of these into your diet:
| Tryptophan-rich foods: | dairy, poultry, nuts and seeds, grains |
| Magnesium-rich foods: | bananas, soybeans, cashews, almonds, salmon, low-fat yoghurt, wheat |
| Calcium-rich foods: | low-fat milk, cheese, broccoli, enriched bread and grains |
| Vitamin B6-rich foods: | pistachio nuts, flaxseed, dried prunes, spinach, bananas |
There’s quite a lot to circadian rhythms! Especially the one which controls your sleep-wake cycle. First and foremost, it’s important to understand that it’s a real thing, and the connection to light and the time of day are key. For those struggling to keep a sleep routine, it’s important to do all you can to get yours back in order. Avoiding blue light and eating sleep-inducing foods is a good start. Try our Sleep Cycle Calculator to find out how many sleep cycles you need to feel truly rested.
