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Sleep Patterns, Biological Clock Adaptation, and Effects on Professional Bodybuilding in Prolonged Continuous Night or Day Environments

Biyolojik Saat Adaptasyon

About the Author

IFBB PRO COACH CAN ÜNAL is one of Turkey’s most experienced and respected IFBB Pro League coaches. He has long been active in the professional bodybuilding scene, both in athlete development and stage mentoring. Expert in the integration of science-based training, nutrition, sleep, and hormone protocols, Can Ünal deeply investigates biological rhythm and hormonal adaptation processes to optimize the performance and health of professional league athletes. He especially develops unique protocols related to sleep regulation and circadian rhythm adaptations that enhance professional athlete performance.


Introduction

In some parts of the world—particularly within the Arctic Circle—people experience extreme environmental conditions where night or day lasts continuously for several months each year. This situation affects human circadian rhythm, thereby impacting sleep quality, hormonal balance, and performance processes. In high-anabolic sensitivity sports like professional bodybuilding, such biological challenges can create significant impacts on performance.

This article examines in detail the adaptation of the human biological clock to prolonged continuous night or day environments, changes in circadian frequency, hormonal secretions, and how these factors reflect on professional bodybuilding environments such as the IFBB Pro League.


1. Natural Mechanism and Adaptation Process of Circadian Rhythm

The term circadian rhythm comes from the Latin words “circa” (about) and “dies” (day), describing biological processes that repeat approximately every 24 hours. This rhythm enables the organism’s internal biological clock to synchronize physiological, behavioral, and metabolic functions with environmental changes—especially the light-dark cycle.


2. Central Internal Biological Clock: Suprachiasmatic Nucleus (SCN)

The master regulator of the circadian rhythm is the suprachiasmatic nucleus (SCN) located in the hypothalamus of the brain. The SCN receives light signals from the retina and communicates them to body systems to maintain the 24-hour rhythm.

  • The SCN consists of approximately 20,000 neurons capable of rhythmic self-activity.

  • Light is detected by photoreceptors in the retina and transmitted to the SCN via the retino-hypothalamic tract.

  • The SCN processes environmental light signals through biochemical and genetic mechanisms to regulate hormone

  • secretion, body temperature, metabolism, and behavior.


3. Molecular Mechanisms and Genetic Clock

The molecular mechanism that drives circadian rhythm is based on intracellular gene cycles:

  • Transcription factors CLOCK and BMAL1 activate production of PER (Period) and CRY (Cryptochrome) proteins.

  • PER and CRY proteins accumulate inside the cell and inhibit CLOCK and BMAL1 activity via negative feedback.

  • This cycle takes roughly 24 hours, allowing cells to establish their internal clocks.


4. Physiological Effects of Circadian Rhythm

The circadian rhythm governs timing of key physiological processes:

  • Sleep-wake cycle: Initiated by melatonin secretion at night and waking triggered by morning cortisol surge.

  • Hormone secretion: Timing of growth hormone (GH), cortisol, insulin, and others depends on circadian rhythm.

  • Body temperature: Fluctuates throughout the day; low in morning, high in evening.

  • Metabolism and energy use: Nutrient intake and energy expenditure are optimized according to circadian cycles.


5. Role of Environmental Factors

  • Light: The strongest synchronizer (“zeitgeber”) aligning circadian rhythm to environment. Artificial light at night can disrupt rhythm.

  • Meal timing: Eating patterns influence circadian rhythm and metabolic processes.

  • Physical activity: Exercise timing also helps regulate the biological clock.


6. Disruption of Circadian Rhythm

Conditions such as jet lag, shift work, and prolonged day/night periods in polar regions can disrupt circadian rhythm.

Such disruptions may cause sleep problems, hormonal imbalances, metabolic diseases, and performance decline.


Summary

The circadian rhythm is an internal biological clock governing many bodily systems on a roughly 24-hour cycle. Managed by the SCN and influenced by environmental cues, it synchronizes sleep, hormone secretion, metabolism, and behavior. Maintaining this rhythm is essential for health and optimal performance.

1.1 Circadian Rhythm and Biological Clock

The human internal clock coordinates all body systems with a roughly 24-hour circadian rhythm, regulated by the hypothalamic SCN and primarily influenced by the light-dark cycle (Czeisler et al., 1999).

1.2 Adaptation and Frequency Changes

  • In polar regions or areas with extreme day-night shifts, natural light cues can disrupt rhythm.

  • The body can adapt its circadian frequency to be slightly longer or shorter than 24 hours (Duffy & Czeisler, 2009).

  • This adaptation leads to “free-running” or “free rhythm” sleep cycles, with individuals developing varied sleep-wake patterns.

  • Melatonin secretion, cortisol rhythm, and other hormone cycles adjust during this adaptation (Lewy et al., 1980).

1.3 Biochemical Basis of Adaptation

  • Melatonin: Transmits darkness signal to the brain to initiate sleep. Continuous light suppresses its production (Arendt, 1998).

  • Cortisol: Stress and wakefulness hormone; timing of secretion shifts with adaptation.

  • Growth hormone (GH): Secreted mostly during deep sleep; fluctuates with changing sleep quality.


2. Sleep Patterns and Bodybuilding in Long-Term Night/Day Environments

2.1 Sleep Quality and Hormonal Cycles

  • Normally, deep sleep and REM peak between 00:00 and 02:00, crucial for GH release and brain recovery (Van Cauter et al., 2000).

  • In day sleepers, this period may fragment or shift due to light and external stimuli.

  • The body reorganizes sleep stages and hormone secretion according to the new biological rhythm, influenced by genetic and environmental factors (Beersma & Daan, 1993).

2.2 Impact on Professional Bodybuilding and Performance

  • Muscle repair and protein synthesis rely on GH secretion; irregular GH release can delay recovery.

  • Changes in sleep and hormonal rhythms complicate optimization of anabolic windows and nutrition timing.

  • IFBB Pro athletes must individualize training and nutrition plans considering their biological clock adaptation.


3. Practical Implications for IFBB Pro League Athletes’ Biological Clock Adaptation

3.1 Sleep Protocol and Training Timing

  • Day sleepers should ensure total sleep duration is sufficient and that deep sleep phases are fully completed.

  • Training should be scheduled according to personal hormonal and energy peaks.

  • For example, waking and training are recommended around the end of melatonin rise and beginning of cortisol increase.

3.2 Nutrition and Hormonal Support

  • Protein and carbohydrate intake should be aligned with anabolic windows.

  • Effects of hormone supports (GH, insulin, testosterone) should be evaluated together with circadian changes.

  • Hormonal fluctuations should be optimized within the sleep-nutrition-training cycle.


4. Conclusion

In individuals living prolonged continuous night or day cycles, biological clock and circadian rhythms change significantly, but human bodies can adapt. However, in performance-demanding sports like professional bodybuilding, this adaptation requires careful planning of training, nutrition, and hormone support. IFBB Pro League athletes must analyze their personal biological rhythms and develop optimized protocols to maintain both performance and health.


References

 
 
 

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