Biorhythm – your body's inner wisdom worth listening to
Have you ever noticed that some mornings you wake up naturally before your alarm, full of energy, while on other days you feel foggy even after noon? Or that your creativity seems to flow freely at a certain time of day, while at other times your thoughts refuse to organize themselves?
This is no coincidence. Your body follows a precise biological rhythm, and it has been listening to it long before you even noticed it.
I first heard about biorhythms on the Kuulopuhetta podcast and started researching the topic in more detail. It's a fascinating subject and certainly goes hand-in-hand with a natural lifestyle. I recommend listening to the Kuulopuhetta podcast to everyone, because it has given me so many "aha" moments and allowed me to delve a little deeper into the functioning of the human body.
What exactly does biorhythm mean?
A biorhythm is the body's internal clock that controls almost all our physiological processes, including sleep, alertness, body temperature, hormone production, metabolism, and mood.
The most important of these is the diurnal rhythm, or circadian rhythm. It is a biological cycle of approximately 24 hours, regulated by the suprachiasmatic nucleus located in the hypothalamus of the brain, which is the body's master clock.
This clock primarily responds to light. Natural morning light kick-starts the day, and the setting sun prepares the body for rest. When you live in accordance with this rhythm, your body functions at its best. When you go against it, stay up late, expose yourself to blue light in the evening, or eat irregularly, the clock falls out of sync.
How does biorhythm manifest in practice throughout the day?
Your body is not the same all day long. Every moment has its own biological purpose.
Morning - waking up and getting started
Body temperature begins to rise even before waking. Cortisol, often mistakenly called the "stress hormone," is highest in the mornings. This doesn't mean stress, but rather energy, as it awakens the body, sharpens the mind, and prepares you for the day. This is a natural, necessary peak.
In the morning, the brain is at its best for analytical thinking and tasks requiring concentration.
Midday - performance peak
Late morning and early afternoon are the peak times for physical and cognitive performance for most people. Reaction time is fastest, muscle strength is at its highest, and coordination is at its best. It's no wonder that athletes often break records in the afternoon rather than in the morning.
Early afternoon — natural slowdown
For many people, 1–3 PM brings a slight feeling of fatigue. This is not due to lunch, but is biological. In many cultures, this time is reserved for a rest, and for good reason. A short 10–20 minute rest at this point significantly restores alertness without disturbing nighttime sleep.
Evening — winding down
As the sun sets, the body's cortisol levels drop and melatonin production begins. Body temperature slowly starts to decrease. The body prepares for rest, even if the mind doesn't always follow.
This is the body's message: slow down. Dim light, calmness, and warmth support this natural transition. It's wise to consciously calm your environment, for example, by reducing exposure to excess blue light, to allow your normal biorhythm to function.
Why do so many of us live against our biorhythm?
Modern lifestyles and structures are in many ways at odds with our biological clock. We stare at blue light screens a lot during the day, live in homes where blue lights are the primary light sources, and spend far too little time in nature, where we could get closer to a natural rhythm.
Blue light pollution affects our melatonin production, causing it to be delayed, making it harder to fall asleep, and impairing sleep quality.
Irregular mealtimes, in turn, disrupt the body's so-called peripheral clocks. The liver, intestines, and other organs have their own biological rhythms that synchronize through eating.
Social jet lag, on the other hand, is a situation where the sleep rhythm of the weekend differs from that of the weekdays. Studies have linked it to fatigue, mood swings, and metabolic challenges. So it's no wonder if staying up late on the weekend still makes you feel tired several days later.
What happens when the biorhythm is disrupted?
Long-term disruption of the biorhythm is not merely a problem of fatigue. Studies show it is linked to many factors that impair well-being:
- Sleep quality deteriorates, recovery slows down
- Mood changes more easily
- Concentration and memory suffer
- The body's inflammatory responses may intensify
- Hormonal balance is disturbed
People who do shift work or cross many time zones experience this concretely, but the same phenomenon also occurs more slowly and imperceptibly in daily life, when small choices accumulate.
How to start living in accordance with your biorhythm?
The good news is that your body wants balance. It doesn't require a complete life overhaul, but small, repeated choices that lead in the right direction.
Light guides everything — use it consciously
Expose yourself to natural light in the morning as soon as possible after waking up. Even 10 minutes outdoors or by a bright window helps synchronize your internal clock. In the evening, dim the lights, switch to warm tones on screens, put on blue light blocking glasses, and let your brain start to wind down.
Regularity is the biorhythm's best friend.
Your body learns from rhythm. The same wake-up time every day, including weekends, is the most impactful single action. It doesn't mean a rigid schedule, but rather the body's trust in when it's time to wake up and when to sleep.
Listen to the body's natural energy flows
Instead of forcing yourself to be productive when your body wants to rest, try to align your tasks with your energy levels. Demanding tasks for the morning, creative work for your peak time, calm routines for the evening. This might sound like laziness, but it’s not — it’s wisdom.
A morning ritual anchors the day
A morning routine is not a trend; it is one of the most effective ways from a biorhythm perspective to start the day right. A calm awakening, water, movement, and natural light before screens create a foundation upon which the entire day can be built more balanced.
Winding down in the evening is as important as starting the morning
The quality of sleep is largely determined by how you spend your evenings. Dim lighting, a calm environment, warmth, and an unhurried atmosphere prepare the body for rest better than any sleeping pill. The drop in body temperature in the evening is a physiological signal for falling asleep, so a warm bath or shower before bed paradoxically speeds this up, as the body's temperature drops afterwards.
Biorhythm and natural lifestyle
Living in accordance with your biorhythm is essentially the same as embracing a natural lifestyle: it means listening before fixing, slowing down before speeding up, and understanding before changing. Our bodies have evolved over millions of years to function according to natural rhythms, interacting with light and darkness, warmth and coolness, activity and rest. Modern life has distanced us from these rhythms faster than biology can adapt. And this is perhaps why human suffering has increased, as we are not living in sync with our bodies.
Returning to our body's biological rhythm does not mean giving up anything. It means being aware that you can make small choices in your daily life that respect how your body truly functions.
At Purela, we believe that well-being is built on deliberate, repeated choices, not perfection. Let's take small steps at a time and enjoy the journey towards a healthier daily life.
Purela's selection is built around Morning and Evening Rituals, offering the best options for both times of day. Explore the selections via the links: Morning and Evening
With kindness,
Henriikka
Sources
This article is based on peer-reviewed research and scientific publications. Below are the key references:
Circadian rhythm and health
- Makarem, N. et al. (2021). *Circadian disruption and human health.* Journal of Clinical Investigation. https://www.jci.org/articles/view/148286
- Zheng, X. et al. (2025). *Circadian rhythmicity and human health.* ScienceDirect / Biomedical Journal. https://www.sciencedirect.com/science/article/pii/S2319417025000290
- Grünwald, J. et al. (2025). *Circadian rhythms and human studies: methodology, challenges, and future directions.* Biological Rhythm Research. https://www.tandfonline.com/doi/full/10.1080/09291016.2025.2541247
Biorhythm disruptions and metabolism
- Her, T. et al. (2024). *Roles of the circadian rhythms in metabolic disease and health.* Frontiers / NCBI. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11596197/
- Reszka, E. & Przybek, M. (2016). *Circadian rhythms in environmental health sciences.* Current Environmental Health Reports / NCBI. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7458936/
Cortisol and morning awakening
- McHill, A. et al. (2022). *The circadian system modulates the cortisol awakening response in humans.* Frontiers in Neuroscience / PMC. https://pmc.ncbi.nlm.nih.gov/articles/PMC9669756/
- Garde, A. et al. (2022). *Night work, chronotype and cortisol at awakening in female hospital employees.* Scientific Reports / Nature. https://www.nature.com/articles/s41598-022-10054-w
Social jet lag
- Roenneberg, T., Allebrandt, K.V., Merrow, M. & Vetter, C. (2012). *Social jetlag and obesity.* Current Biology, 22, 939–943.
- Parsons, M.J. et al. (2015). *Social jetlag, obesity and metabolic disorder.* International Journal of Obesity, 39, 842–848.
- Nature Reviews Endocrinology (2023). *How can social jetlag affect health?* https://www.nature.com/articles/s41574-023-00851-2
- ScienceDirect (2025). *Social jet lag and mental health outcomes: A systematic review and meta-analysis.* https://www.sciencedirect.com/science/article/pii/S0001691825007322
Light, blue light, and biorhythm
- ACE Fitness (2025). *The effects of circadian rhythm on physical and mental health.* https://www.acefitness.org/resources/pros/expert-articles/8990/the-effects-of-circadian-rhythm-on-physical-and-mental-health/
