Your Body Already Knows When to Work, Rest, and Heal. Are You Listening to It?
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Feel Fuzzy psychologist, Sakshi, on the mind-body connection, circadian rhythms, and why working with your biology instead of against it might be the most underrated mental health tool you have.
Here is something most productivity advice gets backwards.
We are told to push harder, stay up later, squeeze more out of every hour. But your body is already running on a precise, elegantly timed internal clock, one that has evolved over millions of years to tell you exactly when to be alert, when to be creative, when to exercise, and when to rest. And the more you work against it, the more it costs you: in energy, in mood, in mental health.
That clock has a name. It is called the circadian rhythm.
What Is a Circadian Rhythm?
Circadian rhythms are the natural biological processes that repeat in approximately 24-hour cycles, regulating everything from when you feel sleepy to when your body temperature peaks to when your muscles are at their strongest.
The word comes from the Latin circa diem, meaning “around a day.” And the rhythm’s movement closely mirrors the sun’s. As light enters the environment, the body activates. As darkness arrives, it begins to wind down toward rest.
Research published in PNAS in 2024 confirms that sleep, circadian rhythms, and mental health are reciprocally interlinked: disruption to the quality, continuity, and timing of sleep can precipitate or exacerbate psychiatric symptoms in susceptible individuals, while treatments that target sleep and circadian disturbances can alleviate psychopathology. In other words, your circadian rhythm is not just about when you feel tired. It is a window into your mental health.
The Clock in Your Body: A Timeline
To understand how powerful this rhythm is, consider what your body is actually doing across a 24-hour cycle:
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7:30 am: Melatonin secretion stops. Your body signals that sleep time is over.
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10:00 am: Peak alertness. Cognitive performance is at its highest.
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2:30 pm: Best coordination. Fine motor skills are sharpest.
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3:30 pm: Fastest reaction time.
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5:00 pm: Greatest cardiovascular efficiency and muscle strength. The ideal window for physical exercise.
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7:00 pm: Highest body temperature.
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9:00 pm: Melatonin secretion begins. Your body starts preparing for sleep.
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2:00 am: Deepest sleep.
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4:00 am: Lowest body temperature.
This is not a rough guide. This is your biology, running like clockwork, every single day. The question is whether you are working with it or against it.
The Cortisol and Melatonin Story
Two hormones sit at the heart of the circadian rhythm: cortisol and melatonin.
Cortisol is often called the stress hormone, but that framing misses something important. Research published in the journal Sleep in 2024 confirms that cortisol is the central timing signal for peripheral organs responsible for whole-body metabolism, and that disruption to this rhythm leads to desynchrony, insulin resistance, and broader physiological consequences. In the morning, cortisol rises naturally to help you wake up, focus, and take on demanding cognitive work. It is not a sign of stress. It is your body’s way of giving you fuel.
Melatonin, on the other hand, is your body’s darkness signal. It begins rising around 9pm, telling your body that the environment is becoming less safe for activity and that it is time to rest. When you sit down to do focused, demanding work at 10pm, you are fighting directly against this signal. Your melatonin is rising, your cognitive performance is declining, and the work that might have taken you an hour at 10am can take three at 10pm — with lower quality output.
What Circadian Disruption Does to Mental Health
This is where the mind-body connection becomes particularly important.
Research in Frontiers in Psychiatry confirms that circadian rhythm disruptions are not standalone phenomena, they are closely linked to a range of neuropsychiatric conditions, including depression, bipolar disorder, and anxiety. The relationship runs in both directions: disrupted sleep worsens mental health, and poor mental health disrupts sleep. Severity of circadian misalignment has been found to correlate directly with the severity of depressive symptoms.
This means that anxiety, depression, low mood, and poor concentration are not always purely psychological problems to be solved by purely psychological means. Sometimes they are also biological signals. Signs that the body’s internal clock has been disrupted, and that bringing it back into alignment could meaningfully shift how a person feels.
Why Daytime Sleep Does Not Work the Same Way
One of the most common complaints people bring to therapy is feeling exhausted despite sleeping. And often, on closer examination, the issue is not just how much they are sleeping but when.
Sleeping during the day does not offer the same restorative quality as sleeping at night, and the reason is biological. Melatonin levels are naturally low during daylight hours. Light signals to the brain that the body should be awake and active, which means the brain is working against its own rest when it tries to sleep in a lit environment. The result is lighter, less restorative sleep, which can leave a person feeling groggy, irritable, and lo; adding to, rather than relieving, stress and low mood.
This is not a character flaw. It is physiology.
Working With Your Rhythm Instead of Against It
The circadian rhythm is, as I often describe it to my clients, like a lighthouse. It is already there, already doing its job, already showing you the safest route. The question is whether you are navigating by it.
Some practical ways to begin working with your rhythm rather than against it:
Protect your mornings for your most demanding cognitive work. Between roughly 8am and noon, alertness and cortisol are at their peak. Use this window for tasks that require focus, problem-solving, creativity, or important decision-making.
Move your body in the late afternoon. The 4-6pm window is when cardiovascular efficiency and muscle strength peak. Even a 20-30 minute walk during this time uses your biology rather than fighting it.
Wind down before 9pm. This does not mean going to sleep at 9pm. It means beginning to slow down: dimming lights, reducing screen stimulation, moving away from demanding tasks. Your melatonin is rising whether you acknowledge it or not. Giving it the right environment allows it to work.
Guard your sleep environment. Darkness facilitates melatonin production. A cooler, darker room signals to the body that it is safe to enter deep sleep.
Stress, Anxiety, and the Circadian Connection
In my practice, I work with an integrated approach that includes circadian rhythm optimisation alongside therapeutic work. And what I have seen repeatedly is that lifestyle changes aligned with the body’s natural rhythm can work as a genuine complement to healing from stress, anxiety, and depression — not as a replacement for therapeutic or medical support, but as a meaningful layer of it.
Your body is not working against you. It is working for you, constantly, on a schedule it has maintained for your entire life. Stress, anxiety, and low mood are not just states of mind. They are also states of body. And one of the most powerful things you can do for your mental health is to start listening to what your body is already telling you.
The rhythm is already there. You just have to learn to follow it.
- Sakshi Singhania, Counselling Psychologist, Feel Fuzzy
Want to explore this further?
This piece was written by Sakshi Singhania, counselling psychologist at Feel Fuzzy. Sakshi uses an integrated approach combining Integrated Somatic Trauma Therapy, Cognitive Behaviour Therapy, and Circadian Rhythm Optimisation, helping clients understand the deep connection between mind and body while building practical tools for everyday life. She has supported 2000+ individuals across India, the USA, the UK, Canada, and beyond.
If you would like to explore how your lifestyle, sleep patterns, and daily rhythms might be affecting your mental health, you can learn more about working with Sakshi here.
References
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Wulff, K., et al. (2024). The sleep-circadian interface: A window into mental disorders. Proceedings of the National Academy of Sciences, 121(9).
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Liu, P.Y. (2024). Rhythms in cortisol mediate sleep and circadian impacts on health. Sleep, 47(9).
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Kitajima, T., & Kuriyama, K. (2023). Editorial: Circadian rhythm sleep-wake disorders: Pathophysiology, comorbidity, and management. Frontiers in Psychiatry.
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Richter, K., & Penzel, T. (2023). Editorial: Circadian rhythms of mental health. Frontiers in Network Physiology.
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Blagrove, E., et al. (2024). Unraveling the interplay of circadian rhythm and sleep deprivation on mood. PLOS Digital Health, 3(1).