Do you sleep badly? How the biological clock and circadian rhythm influence sleep

The human body works according to an internal clock known as the circadian rhythm. This system plays a part in organising multiple biological functions, such as sleep, appetite, body temperature, hormone production, energy levels and mood.

This rhythm is naturally synchronised with the cycle of light and darkness, i.e. the rising and setting of the sun. Over the course of evolution, the human body has adapted to this pattern, using light as the main warning signal and the absence of light as a rest signal.

When daily habits persistently deviate from this cycle, for example by going to bed late on a regular basis, waking up to sudden stimuli, spending long periods exposed to artificial light at night or keeping very irregular hours, the body may find it more difficult to organise its internal rhythms properly.

Light and darkness: regulators of the biological rhythm

During the day, exposure to natural light encourages the production of cortisol, a hormone associated with alertness, concentration and energy mobilisation. As the light diminishes towards the end of the day, the body tends to gradually increase the production of melatonin, a hormone that is essential for inducing sleep and for the processes of cell recovery and regeneration.

Today's lifestyle, characterised by constant artificial lighting, prolonged use of screens and irregular schedules, can interfere with this natural transition. Exposure to bright light at night can delay the release of melatonin, making it difficult to fall asleep and jeopardising the continuity and depth of sleep.

Over time, this mismatch can be reflected not only in night-time rest, but also in metabolism, hormonal balance and emotional regulation.

Signs of possible circadian rhythm maladjustment

Some signs that may suggest a maladjustment of the biological rhythm include:

• Difficulty falling asleep or waking up, even after several hours of sleep

• Persistent feeling of tiredness, irritability or difficulty concentrating

• Frequent need for caffeine to start the day

• Weight changes without significant changes in eating habits

• Anxiety or mood swings with no apparent cause

These signs do not in themselves constitute a diagnosis, but may be associated with changes in the organisation of the circadian rhythm.

Strategies to support biological rhythm regulation

A few simple measures can help promote better organisation of the circadian rhythm:

• Wake up to natural light whenever possible, avoiding sudden stimuli

• Expose yourself to sunlight in the morning by opening windows or spending some time outdoors

• Reduce exposure to blue light at the end of the day by limiting the use of screens or using suitable filters

• Maintain relatively consistent bedtimes and wake-up times, including at weekends

• Practise physical activity preferably in the morning or early afternoon

• Opt for lighter meals at dinner and avoid eating within two hours of going to bed.

• Create a dark, quiet and cool night-time environment without electronic devices in the room

These strategies must always be adjusted to each person's needs, context and moment in life.

Sleep from an integrative perspective

Sleeping well isn't just about spending more hours in bed, it's about respecting the body's biological rhythms as much as possible. Aligning your lifestyle with the natural cycle of light and dark can support hormonal regulation, metabolism, immune function and emotional stability. This alignment tends to translate into a greater sense of energy, better recovery capacity and improved quality of life.

It's not always easy to adjust your habits to the so-called 12/12 rhythm, the approximate balance between periods of light and darkness that human biology has evolved for. Even so, small consistent changes, maintained over time, can have a significant impact on the organisation of sleep and the overall regulation of the organism.

Respecting the biological rhythm doesn't mean striving for perfection, but creating conditions that favour self-regulation and a more balanced relationship with sleep and health.

Biorhythms and sleep organisation are topics that are frequently addressed in Integrative Osteopathy consultations, which are framed by Clinical Psychoneuroimmunology. This approach considers the interaction between lifestyle habits, the nervous system, the endocrine system and each person's individual context. Through an individualised assessment of sleep patterns, circadian rhythm and the various factors that can interfere with physiological regulation, it becomes possible to better understand the mechanisms involved and support the definition of strategies tailored to the needs and specific context of each individual.