How Do Circadian Rhythms Affect Human Performance

Circadian Performance

Whether you have heard of Circadian Rhythms or not, if you are reading BodyWeight Heaven you have an interest in your health and performance. In this article, we will discuss how circadian rhythms affect human performance.

Have you ever wondered how the terms “morning lark” or “night owl” came to be?

While there are (very blessed) people whose energy and productivity levels rise along with mister sun, there are also those who find it impossible to survive mornings without a humongous cup of coffee. You might even have that crazy friend who sets about ten alarms with less than five-minute gaps in between each one!

In the same way, some may have committed to jogging as a part of their early morning routine, and some prefer the chill breeze in their evening runs.

Many people think that these are just a matter of preference or learned habits. However, our good pal science has some pretty mind-blowing explanations behind the so-called body clock.

From sleep-wake patterns to even your meal times, let’s dive into how circadian rhythms affect human performance.

What is the Circadian Rhythm?

Sun and Calm

You might not even notice it, and you may even try to ignore it, but your body follows a pattern on when to eat, sleep, and wake every day.

Did you know that your circadian rhythm can help determine when you’d feel most energized and when you’d be up for nothing but rest? Basically, it can affect your psychological and biological alertness levels throughout the entire day and night.

Science generally labels people into either morning larks or night owls. However, researchers have helped to uncover and evolve these chronotypes. With the knowledge that is being gathered, we may soon have another tribe for those who are at their A-game in the afternoon at about 3:00 PM and another after breakfast at 10 AM.

Let’s explore a bit of geek talk and look into your anatomy.

In your brain sits the hypothalamus and inside of this reside a group of neurons we can call the suprachiasmatic nucleus. They are responsible for processing signals from your environment into a series of commands for your body. Basically, synchronizing your body clock.

What are the factors that affect Circadian Rhythms?

Sleepy Bed

When you lie on your bed in total darkness, your eyes’ receptors will become aware of the lack of light in your environment. The signal of darkness is then relayed to your suprachiasmatic nucleus. This then gives the go signal for melatonin production – a hormone that triggers the feeling of sleepiness.

It is not just light that influences your circadian rhythm. Your body can also pick up other external cues. These include things such as temperature, magnetism, and other natural biologic processes. Genetic factors also are at play here. All of which can also guide an individual’s circadian rhythms. 

Your lifestyle can also affect these rhythms, specifically the amount of sleep you allow yourself to have. This can be bad news for people who barely get six hours of snooze time each night – sleep deprivation or restriction can sabotage your neurological functions (e.g. attention, cognition, and memory). 

This is why students are highly discouraged from cramming an entire semester’s worth of studies into one all-nighter! You may be capable of scanning through tons of modules, but don’t expect to remember them all for tomorrow morning’s test!

Moreover, specific medications can also have an impact on your appetite and your sleep/wake cycle. Ensure you know what is going into your body, whether a pill, supplement, or food, and understand their side effects as they may either help induce sleep or make it really difficult to doze off at night.

Science is already aware of the most common factors that map out varying circadian rhythms and ongoing research is being conducted so that we may be able to accurately predict how biomarkers can enhance or disrupt people’s performance. That said, there is little doubt that circadian rhythms affect human performance. They play a vital role in both your physical and cognitive performance.

Why is Circadian Rhythm important?

Sleepy Koala

What if we tell you that circadian rhythms played a vital role in the evolution process of humans and animals? Our environment has shaped us through that process and vice-versa our physical and psychological patterns determine our ability to prepare and adapt to changes in our environment. 

With this, modern researches have associated circadian rhythms to our general health and human performance. Those with disrupted body clocks are more vulnerable to mental and physical illnesses.

Moreover, relationships and careers are greatly affected by the ability to concentrate and stay productive. Don’t expect to get that promotion if you’ve been a notorious sleeper at midday! Messed up body clocks can also drive the rude, cranky monsters in us, increasing our chances of making bad decisions or dropping impulsive statements.

So, How do Circadian Rhythms Affect Human Performance?

Here is a bold statement: 

circadian rhythms have command over the physical and cognitive performance of human beings. 

Allow us to walk you through how this happens.

Physical Effects

Here’s what happens in a typical adult’s 24-hour cycle:

  • Your lowest body temperature can be recorded at about 4:30 AM, while it usually maxes out at around 7:00 PM
  • The average adult’s highest alertness level is around 10:00 AM. One’s body coordination is at its best at about 2:30 PM

Let’s explore how your body clock affects your physical performance using the lens of fitness and sports. 

In this study, researchers sought to analyze the impact of circadian rhythms on people’s capability to adapt their hormones and muscles to their executed exercises, and the results were eye-opening.

Apparently, the primary driving force for fitness enthusiasts’ performance is temperature. Humans can generally reach their peak physical capacity in the early evening when our core body temperature is at its maximum. The hotter you feel, the more ideal your metabolism and muscle compliance will be to reach peak performance.

This can explain why your workout sessions should start with a warm-up. It seems like you literally have to raise your temperature to get the most out of your exercises.


Circadian rhythms also help experts predict the outcome of competitive tournaments such as the National Football League (NFL). Research has been conducted looking into gameplay across timezones on athletes’ performance. For Monday night games that usually start at 9:00 PM, the East Coast team had to deal with an inherent disadvantage, and the West Coast team had an advantage. The east coast team had to play hours beyond their optimum time for cardiovascular capacity and strength while the west coast team was working within their optimum performance time for the day. This was demonstrated to influence the outcome of the game in favor of the west coast teams.

This demonstrates, that if you are looking to maximize your personal performance, health, and life you should be personalizing the time of your workouts and doing your best to synchronize your Circadian clocks. There are numerous ways to do this and in future articles, we will dive into many lifestyle hacks that can help you maximize your physical circadian capabilities.

Cognitive Effects

Aside from the physical aspects, multiple studies have proven that circadian rhythms play a significant role in our basic neuropsychological processes namely attention, memory, and executive functions. You may notice there are periods of time when you feel and respond quickly and there are times when you just feel like a super outdated computer with constant lags and blue screens!

Let’s look at some intriguing research that has found a link between the quality of one’s decision-making process to specific times of the day when they experience fatigue: 

Circadian Cognition

Let’s take parole-board judges for example. At the start of their workday, the proportion of favorable rulings peak at 65% and continuously drops to almost zero as long deliberation hours go by. What’s interesting is that the ratio returned to 65% after judges had their recess or break.

Meanwhile, age has also been revealed to affect circadian rhythms and cognitive performance. The average young adult can exhibit the highest recognition accuracy in the afternoon, while older people have peak capabilities in the morning.

As humans age, sleep also becomes harder to induce, including staying asleep, and remaining alert when awake. Remember when we talked about the hypothalamus at the very beginning? Well, this is because your suprachiasmatic nucleus’ electrical activity gets weaker as you age. The result? Muffled and untimely commands for your body, getting old sucks doesn’t it!

Scientists have also shown interest in how sleep deprivation can disrupt our internal clocks, may it be due to our personal lifestyles or an actual disease (e.g. insomnia). In general, lack of adequate rest has been associated with reduced mental sharpness. 

A study by Waller et al. (2015) backed this up after testing middle-aged men. Those who suffered from acute to chronic sleep deprivation got lower scores in given assessments that dealt with memory, processing speed, and executive function. 

What happens if you mess up your Circadian Rhythm?

For people who travel a lot or work night-shifts, often feel like their body’s internal clock is messed up. Natural morning larks can be forced to work until ungodly hours and have time for sleep only when the sun comes shining. The results can range from mild discomforts to alarming complications:

  • Noticeable reductions in physical and cognitive performance
  • Slower reaction times
  • Uncontrollable weight gain or obesity
  • Increased risk of diabetes
  • Clinical insomnia
  • Hypertension
  • Increased mortality rates
  • Circadian rhythm disorders (e.g. delayed or advanced sleep phase disorder)

How can you improve your Circadian Rhythm?

So, all this begs the question, how can you improve your circadian rhythm? Well, if you know or feel that you have an unhealthy circadian pattern? Don’t fret, it’s still possible to achieve a body clock that keeps you healthy both physically and mentally. This can be among the best forms of self-love you can give your body!

Gather up your commitment and perseverance. Use the tools and tips below maximize your Circadian Rhythms Affect on Human Performance

Sunrise for wakefulness

Be friends with the sun

Try to use light as the primary driver of your body clock. It can be as basic as using the sunrise as your natural alarm clock. Consider sunset as your signal to lay low from work and rest. 

One trick, as the sun rises, expose your eyes (no sunglasses!) and your body to as much of the sunlight as possible. Moreover, getting enough UV light will not only signal your circadian clock properly but will give you your daily dose of vitamin D. Just 15 minutes of exposure to early morning sun can help awaken you. You’ll feel more refreshed doing this and ready to face another busy day.

Ensure you time your meals accordingly

The food you eat will be your main source of strength and energy for the rest of the day. Try to start with a protein-rich breakfast rather than your usual sugar-heavy meals. Depending on your dietary plans, it’s also important to adhere to consistent feeding times so you won’t mess up your circadian rhythm and metabolism rate. Another big factor is to stop eating within 2 hours before you will be going to bed and try not to eat after the sun has set.

Sleep in dark rooms

Remember what we said about melatonin? You can use this knowledge of how melatonin is produced to your advantage. Since its secretion is triggered by darkness, ensure your sleep environment is completely dark. If necessary use an eye mask and install blackout curtains. Be careful as even your skin has receptors and can sense light. The darker your sleeping environment, the better you can achieve deep sleep. Deeper sleep will better facilitate your body’s process of repairing and refreshing itself.

Keep your bedroom comfy

Try to avoid bringing any work into your bedroom, and keep it as a place exclusive for rest. This way, your mere presence in it can trigger your brain into thinking that it’s time for sleep. Depending on your preference, design your bedroom to provide maximum comfort and promote sleep. Invest in ultra-soft sheets, aromatic candles, or even play nature sounds to stimulate relaxation.

Schedule your bedtime and commit to it

Our body has an ideal circadian rhythm, establish a time for sleeping, and stick to this schedule as much as you can. This means no more snoozing off your alarm multiple times! When it’s time to wake up, get out of bed pronto, and start your morning routine. No more of the “another five minutes won’t hurt” excuse, okay? These techniques should prevent excessive sleepiness when you wake up in the morning!

Keep your gadgets away when it’s bedtime

Turn the wi-fi off. Place your smartphone away from your bed. No more last-minute scrolling through the internet when it’s time for sleep! Otherwise, the light from your gadget’s screen can throw off your body clock. This can make it really stressful to get some sleep, and you’d end up wide awake at late night, tossing and turning for hours.

Try blue light glasses

With advancements in technology comes new health risks. While most blue light comes from the sun, technology such as laptops, smartphones, and televisions increase this exposure even further. I have invested in a really good set of blue-blocking glasses and wear them anytime the sun has set to limit my exposure to artificial blue light at night. Also, if you’re working in front of a screen for more than six hours every day, you should consider using daytime blue blockers as well. These products can help prevent eye diseases, reduce eye strain, and improve your sleeping habits. In turn, synchronizing your circadian rhythms, and also your human performance.

Determine your chronotype

While you should use the sun as your guide, It’s no secret that self-evaluation can help you control your strengths and weaknesses. Being aware of your chronotype (e.g. morning lark or night owl) can help you plan and schedule your daily activities in accordance with your peak performance levels. Working or exercising when your body is most ready is a surefire tactic to reap maximum benefits.

Final Thoughts


What seemed like a simple conversation starter actually has a significant impact on one’s quality of life. Being aware of how your Circadian Rhythms Affect Human Performance can do wonders for your physical and cognitive capabilities. 

Better workout results. Enhanced productivity. Generally great moods. We can’t stress enough how beneficial it is to nurture an ideal body clock!

Feel free to share this article and help out your peers whose morning routines start with hitting the snooze repeatedly!

Got any personal tips and tricks for improving circadian rhythms? Let’s chat about them in the comments below!

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