You probably already know that your body goes through different cycles each and every day. Our Circadian rhythm reflects our waking and sleeping cycles in conjunction with sunlight (shout out to the pineal gland in our post about the endocrine system!). Women are aware of their menstrual cycles (as well as men in committed relationships, bring home some chocolate fellas!) and men even have hormonal cycles as well (so ladies bring home some chocolate too!). Sometimes we feel like we’re on autopilot or feel like Bill Murray in the movie Groundhog Day, going through the same motions over and over again.
But did you know that there is a time of day where different organs of your body tend to function more efficiently? Or that your muscles and joints can be up to 20% more flexible at night compared to when you first wake up? Or that most world records are broken during the day and the early evening? Or that you can use this knowledge to help cope with jet lag and adjusting to a new time zone?
This natural phenomenon is referred to as our “body clock”. This body clock is prevalent in many different traditions such as the daily Qi Meridian body clock in Traditional Chinese Medicine and the ayurvedic dosha clock. These traditions track the cycles of where and when energy is used most efficiently for different purposes, such as the best time to eat and the time period when our physical capabilities are at a maximum. These effects can be physical, mental, and emotional. Some studies have even shown that people are more likely to share upbeat news on social media early in the morning and ranting or complaints tend to spike in the evening (somebody tell Donald Trump he’s up past his bedtime!).
Many people like to use the metaphor of an orchestra conductor to represent our genes and cells related to the body clock. These genes help to keep the rhythm of the body regardless of what else is going on. Even if you were to live underground for months at a time with no sunlight your body would continue to function according to its built-in internal clock. All of our organs have their own body clocks and help to make up the different instruments of the orchestra. When we stay up way too late or ignore our body clocks in some way the orchestra of our bodies becomes out of tune.
Knowing about the body clock can help you to optimize many aspects of your day, so let’s explore!
Our bodies are most primed for athletic activities in the afternoon and early evening. Some studies have reported that muscle strength and lung functioning both are at their greatest levels between 2pm-6pm. One such study reported that lung function is over 17% more efficient at 5pm than at midday. Another study reported muscle function can be up to 6% greater than the day’s low during this late afternoon period. This helps explain why a disproportionate amount of Olympic and world records are broken during this time of day. (Perhaps it even helps explain why a football team playing at night can appear sluggish compared to playing at their usual afternoon time slot.)
Light Affects Your Body Clock
The single biggest factor that affects our circadian rhythm and body clock is light. Do you consider yourself a morning person or a night owl? If you are one or the other you likely have a different speed to your body clock than the 24 hour daily cycle. Internal body clock cycles range from around 22 hours (associated with morning people) to 25 hours (associated with night owls). The sunlight that hits our eyes and stimulates our brains helps us to tweak our internal time cycle to match the 24 hours we associate with a typical day.
We can use sunlight and the way it affects the speed of our body clock to help reduce jet lag! Receiving more light in the morning helps us to feel awake sooner and speeds up our body clock. You may have noticed that lots of light coming through the window in the morning helps you wake up. I know that if there is no light entering the room, like sleeping in a basement, my day gets off to a dramatically slower start and it is more difficult to drag my ass out of bed. Contrarily, receiving lots of sunlight in the late afternoon and sunset hours will slow down your body clock making it easier to remain awake and alert later into the night. You can use sunlight to help either speed up or slow down your clock to adjust to changing time zones and cope with jet lag!
As we age our body clocks tend to become less active. Often this is associated with the deterioration of eyesight as we get older. With age the lens of our eyes become more dense and let in less light. Less sunlight means less of our body clock cells are stimulated. This helps explain why older people have trouble sleeping through the night and tend to be early to rise and early to bed. Getting plenty of sunlight helps to boost our mood (levels of depression are typically higher in winter, hence the term the ‘winter blues’) and can help us to regulate our sleeping patterns. Sunglasses are an effective way to prevent sunlight from reaching our eyes so it may not be advisable for older people with less active body clocks to wear sunglasses all the time!
Life and Death’s Most Common Time
The most common time of day for babies to be born is between 3am-5am, the period in which our brains and bodies are in deep relaxation. During this time we tend to be less receptive to pain. How intelligent our bodies are that they prefer to give birth at the most convenient time! (Even if it’s not so convenient for doctors or midwives to be up that late past a typical bed time!)
This time of night is also when we are most likely to pass away naturally from our mortal bodies. A higher proportion of natural deaths occur between 2am-4am than any other time of day as our bodies and brains are less active. Life and death are two sides of the natural life cycle and both are most likely to occur during these hours of deep relaxation.
12 Cool Facts About the Body Clock
- Around age 10 we start going to bed later and later. During adolescence until around age 21 we tend to naturally sleep in the latest we will in our lives. By around 55 we typically start to go to bed closer to the time we did when we were 10.
- The biggest increase in blood pressure happens in the 3 hours after waking. In the morning our blood vessels can’t widen as much as later in the day, creating more resistance to blood flow. During the early hours after waking we are over 3x more likely to have a heart attack than later in the day.
- Cortisol levels (the stress hormone) are typically higher in the morning. This makes us more alert and mentally capable for analytical thinking, usually peaking around 10am-12pm. (This depends on your personal body clock.)
- We are often better able to think creatively at times in the day when we are tired.
Our bodies naturally want to rest in the early afternoon, the time when many cultures take a siesta. Statistics show we are 3x more likely to fall asleep at the wheel while driving at 2pm than at 6pm.
- Studies have shown that chemotherapy administered at specific times of the day when healthy cells are least active is much more effective at eliminating cancerous cells and damages a fraction of the body’s healthy cells verse other times of the day.
- Open heart surgery is less likely to have complications when performed in the afternoon compared to the morning.
- While muscle activity is greatest in the afternoon and early evening, balance is thought to be highest in the morning.
- Current eating habits are contrary to the body’s natural design. Eating a big dinner increases blood glucose levels compared to eating a big breakfast, meaning our bodies aren’t processing and storing energy as efficiently. An old saying goes “Eat breakfast like a king, lunch like a prince, and dinner like a pauper.” This corresponds to the Qi organ clock stating that the stomach has heightened energy from 7am-9am. Studies find variation to this suggestion but usually recommend a small dinner and larger food intake during the hours of activity.
- Studies have shown that sexual performance can be best in the afternoon with our increased body temperatures. However our skin is more sensitive in the evening and some studies state it is easier for women to orgasm in the evening. Men have higher testosterone levels in the morning.
- Our bodies and brains appear to be least affected by alcohol consumption in the early evening. The effects of a few glasses of wine at lunch will usually be felt more than a few glasses of wine at happy hour.
- Increasing Alzheimer’s patients’ exposure to light has been shown to provide comparable results to drugs over a thee year time period while boosting mood instead of creating nausea.
In the hustle and bustle of modern life we are moving further and further away from harmony with our internal body clocks. Is staying up late watching television affecting your ability to perform early in the morning? Are you working a night shift and becoming aware that your mood and health are diminished? How does it feel to make breakfast your largest meal of the day and dinner the smallest? If we want to become more self aware then adhering to our body clocks can be a great way to start. No two people are exactly alike. This applies to our body clocks as well. Becoming mindful of your patterns at different times of the day can help you to discern what sort of activities suit you best at different times of the day. It’s not only important to get plenty of rest and exercise, but to do them at the time that suits your body as well!
Your body clock is ticking. Can you tell the time?
Cooper, Belle Beth. “Master Your “Body Clock” To Eat, Sleep, and Work More Efficiently”. https://lifehacker.com/master-your-body-clock-to-eat-sleep-and-work-more-e-890410373
Gallagher, James. “Heart Surgery Survival Chances Better in the Afternoon”. http://www.bbc.com/news/health-41763958
Shellenbarger, Sue. “The Peak Time For Everything”.
The Secret Life Of Your Bodyclock. BBC. http://www.bbc.co.uk/programmes/b00hxtwc