Why paying attention to your circadian rhythm matters

25 Sep 2024

By Bron Mandile

As if being dictated to by a regular clock wasn’t bossy enough, humans actually have an internal clock that governs our ability to correctly function.

Four internal rhythms: Circadian, Diurnal, Ultradian and Infradian – make up this circadian clock, which follows a cycle that roughly correlates to the patterns of the sun.

In other words, your circadian clock naturally responds to light and dark, regulating many physiological, mental and behavioural changes throughout the day.

The most well-known biological rhythm is the circadian rhythm. It sets the routine of your daily life – when you sleep, feel hungry, energetic or tired. It even helps regulate your body temperature, hormone levels and blood pressure.

Your body naturally sets your circadian rhythm by responding to light and producing hormones like melatonin, cortisol, insulin and leptin. These hormones either make you feel sleepy (melatonin) or alert (cortisol and insulin). Production of other hormones which regulate appetite (like leptin) are also stimulated.

If you’ve ever experienced the impact of jet lag, you’ll know the importance of regulating your circadian clock. When you travel across time zones or overnight, you upset the light regulation your circadian clock relies on, and the result is fatigue, insomnia, gut issues and irritability.

With the circadian rhythm being responsible for whether you are able to achieve deep, restorative sleep, it’s little wonder that being out of sync can have a huge impact on your overall wellbeing. Resulting physical and mental health issues include sleep disorders like insomnia and shallow sleep syndrome, and mood disorders such as depression and seasonal affective disorder (SAD).

Fortunately, despite it being an autonomic function, you actually have a good deal of control over your circadian clock. To foster a regular, healthy, 24-hour rhythm:

Stick to a regular sleep routine – wake at the same time each day and get into bed at a set time, too.

Spend time outside – this exposes you to more natural light (even sitting by a window isn’t as good as the glass blocks some of the necessary ultra-violet rays).

Get plenty of exercise – preferably outside (see above) and early in the morning or early afternoon to feel more alert in the mornings.

Avoid caffeine later in the day – caffeine is a well-known sleep disruptor and that’s because it makes your body delay the production of sleep hormone melatonin.

Don’t take long naps – while a short 10-20 minute nap early in the afternoon can be beneficial, napping longer or later can throw off your sleep-wake rhythm.

Stanford Associate Professor of Neurobiology, Dr Andrew Huberman, says that for optimal sleep, the most important thing is to get plenty of natural light first thing in the morning.

It might feel counterintuitive that what you do first thing can affect your ability to feel tired at night, but getting bright light after waking actually controls the timing of hormone production throughout the day.

In the same way, Huberman says the eye and brain are especially sensitive to light at night, so keeping lighting dim in the evening and avoiding the light of your phone close to bedtime can help make your sleepy.

Getting some sunlight exposure as the sun is setting can also encourage the body to produce adequate amounts of the sleep hormone melatonin at the right time.

All of these tips can bring you better quality sleep, which in turn will make you feel brighter, more alert and energetic throughout the day.

Being better in-sync with your circadian rhythm will also result in more regulated hormone production, which will improve your general mood and overall health.