Ever wondered how your body knows when to sleep? Or why you have more energy at certain times of the day? Or how some people wake up at the same time each day feeling fresh? The last question still eludes me however according to the science it’s likely thanks to their excellent circadian rhythm. Each and everyone of us (even your dog) has one, our own internal 24-hour clock that influences our sleep/wake cycle, metabolic rate, body temperature, hunger, energy levels and even our mood. Super moody? It might be a disruption to your circadian rhythm…read on to find out why.
How it works
Being an approximately 24-hour clock, your circadian rhythm resets each day while you sleep and is controlled by the circadian pacemaker known as the suprachiasmatic (soo-pra-kai-as-ma-tik) nucleus. This is a big name for a tiny speck of thousands of brain cells located in the hypothalamus. Your eyes send messages to the suprachiasmatic nucleus (SCN) about how much light there is so that when it starts to get dark, the SCN can send a message to the body to begin releasing melatonin (sleep hormone) in the lead up to sleep. In the same way, the SCN can also trigger the release of cortisol in the morning to make you more alert.
Other factors affecting your circadian rhythm
As you may have guessed, light isn’t the sole influence of your circadian rhythm, it can also be affected by:
- Physical activity
- Work hours (especially shift work)
- Eating habits
- Traveling across time zones
- Artificial light e.g. screens, bright rooms
What it looks like
Your energy levels rise and fall throughout a 24-hour period as directed by your circadian rhythm. Melatonin release reaches its peak around the middle of the night resulting in your deepest sleep and you will likely feel the most alert around 10am. Hint – schedule your most difficult tasks and meetings mid-morning as you hit your lowest day-time energy around 1-2pm. You will also notice that your heart rate spikes around 6am; this happens to be the most likely time that someone will suffer a heart attack.
Of course, everyone is different with a multitude of variations in lifestyle, work routines, climates and eating habits which we already know impact our internal clocks. Even your chronotype (there now more than just ‘night owl’ and ‘morning lark’) can affect your sleep/wake cycle and your daily energy levels.
Why it matters
Disruptions to your circadian rhythm create a cascade of health issues including obesity, high blood pressure, diabetes, hormone imbalances and even mood disorders. There is growing evidence that internal clock disruptions could be linked to depression and seasonal affective disorder (SAD). The grogginess and poor cognitive function associated with insufficient sleep directly detracts from your ability to perform well at work, maintain positive relationships or even just get to the gym.
A healthy and active lifestyle together with sufficient sleep is crucial to maintaining a healthy sleep/wake cycle. Lucky for you, you’re in the right place to reset and improve yours 😉
Studying the circadian rhythm has been a game changer for me and as a self-confessed-anti-morning-person, I’ve discovered I can harness this knowledge to improve my routine, sleep better, stop afternoon snacking and maybe even not hit the snooze button.