Circadian Rhythm

Circadian Rhythm is the regular recurrence, in cycles of about 24 hours, of biological processes or activities, such as sensitivity to drugs and stimuli, hormone secretion, sleeping, feeding, etc. This rhythm seems to be set by a 'biological clock' which seems to be set by recurring daylight and darkness.

How Does the Suprachiasmatic Nucleus (SCN) Control Circadian Rhythm?

Circadian rhythms are biological cycles within organisms that allow them to adjust their physiology and behavior to anticipate and adapt to changes in the outside environment. Circadian rhythms are maintained with the help of circadian clocks, the main circadian clock in mammals is the suprachiasmatic nucleus (SCN).

The Circadian Rhythm and the Immune System

Artificial Light Exposure and Circadian Rhythm

How Does Airplane Travel Affect the Human Body?

Memory Recall and Circadian Rhythm

Circadian Rhythm Sleep Disorders

Circadian Rhythm Length Variations - Early Birds and Night Owls

Social Jetlag and Sleep

Circadian Rhythm and Weight Loss

Chronobiology: Why Time Matters in Medicine

What is the Circadian Rhythm?

Latest Circadian Rhythm News and Research

New review illuminates the intricate connections between gut microbiota and sleep regulation

A comprehensive review published today in Brain Medicine illuminates the intricate connections between gut microbiota and sleep regulation, establishing the microbiota-gut-brain axis as a critical pathway in understanding and potentially treating sleep disorders.

4 Nov 2025

Aligning your body clock may protect your heart and metabolism, says AHA

A new American Heart Association scientific statement highlights how maintaining circadian health through regular sleep, light exposure, meal timing, and exercise may reduce cardiometabolic disease risk. Disrupting these daily rhythms can impair glucose regulation, blood pressure, and cardiovascular function.

29 Oct 2025

Circadian rhythm disruptions may increase the risk of cardiovascular disease

As modern lifestyles increasingly challenge the body's natural circadian rhythm, the American Heart Association is spotlighting the potential health consequences of regular disruptions to our body's internal clock with a new scientific statement published today in its flagship journal Circulation.

28 Oct 2025

Disruption of glial circadian rhythms linked to Alzheimer's disease progression

Alzheimer's disease is notorious for scrambling patients' daily rhythms. Restless nights with little sleep and increased napping during the day are early indicators of disease onset, while sundowning, or confusion later in the day, is typical for later stages of the disease.

23 Oct 2025

Night shift work may raise risk of irritable bowel syndrome

The study indicates that night shift work increases irritable bowel syndrome risk, particularly among those with obesity, due to circadian rhythm disturbances.

22 Oct 2025

Solar storms linked to increased heart attack risk in women

An article published in the journal Communications Medicine points to a correlation between disturbances in the Earth's magnetic field resulting from solar storms and an increase in the frequency of heart attacks, especially among women.

26 Sep 2025

Drinking less water daily spikes your stress hormone

Findings indicate that low hydration is associated with increased cortisol spikes during stress, potentially influencing long-term health risks.

26 Sep 2025

Daylight saving time does not increase heart attack risk, study shows

A large U.S. registry study of more than 168,000 patients found that daylight saving time (DST) clock changes did not increase heart attack rates or worsen in-hospital outcomes. The findings suggest that the lost or gained hour is unlikely to trigger acute myocardial infarction in contemporary care.

10 Sep 2025

Exploring whether chemotherapy disrupts biological clock in the brain to impair circadian rhythms

During and after chemotherapy, nearly half of cancer patients endure circadian rhythm disruptions, which worsens treatment side effects.

9 Sep 2025

How breast milk changes from day to night and why timing matters

Breast milk's hormonal and microbial variations throughout the day may affect infant development, emphasizing the need for synchronized feeding practices.

8 Sep 2025

New insights into how breast milk supports baby’s internal clock

Breast milk is the first 'super food' for many babies. Full of vitamins, minerals, and other bioactive compounds, it helps build the young immune system and is widely considered the optimal source of infant nutrition.

5 Sep 2025

Intense light therapy boosts heart protection after surgery

Intense light therapy after surgery can increase a critical protein that protects heart tissue while lowering levels of troponin, a protein indicating heart damage that's linked to higher mortality in patients undergoing non-cardiac surgery, according to a study by researchers at CU Anschutz.

4 Sep 2025

Genetics and diet work together to shape daily rhythms of fat metabolism

Our bodies follow a natural 24-hour cycle known as the circadian rhythm that influences everything from sleep to metabolism.

25 Aug 2025

The challenges of shift work on diet, sleep, and well-being

Healthcare shift workers face dietary and sleep challenges, leading to burnout and health issues. Effective interventions are crucial for their well-being.

25 Aug 2025

Gut bacteria and insomnia influence each other in small but significant ways, study shows

Scientists used Mendelian randomisation to explore the two-way relationship between gut microbiota and insomnia, analyzing GWAS data from over 386,000 individuals and two major microbiome cohorts. The study found only limited taxa surviving strict correction, suggesting small but causal links that highlight the gut–brain axis in sleep health.

21 Aug 2025

How circadian biology shapes intestinal regeneration and health

The interplay between the circadian clock, intestinal stem cell niche, and epithelial cell fate is shaping our understanding of how gut homeostasis and cellular regeneration are regulated.

14 Aug 2025

Does your morning coffee or tea really boost your mood? Here’s what science says

Caffeine consumption is linked to increased positive mood in daily life, especially within 2.5 hours after waking. This effect is influenced by tiredness and social context, with no consistent impact on negative emotions.

6 Aug 2025

Breast milk fatty acids help babies sleep longer, study finds

Researchers found that higher levels of polyunsaturated fatty acids (PUFAs) in human milk are associated with longer sleep duration in exclusively breastfed two-month-old infants. The strongest effects were observed for daytime (diurnal) sleep, especially with omega-3 and omega-6 fatty acids.

5 Aug 2025

Study finds significant associations between sleep traits and 172 diseases

A groundbreaking international study, recently published in Health Data Science, analyzed objective sleep data from 88,461 adults in the UK Biobank and found significant associations between sleep traits and 172 diseases.

28 Jul 2025

Bioprinted implants restore hormone function in adrenal insufficiency

Adrenal hormone function was restored in animal studies, potentially paving the way for a functional cure for primary adrenal insufficiency in humans, according to research being presented by Aspect Biosystems on Monday at ENDO 2025, the Endocrine Society's annual meeting in San Francisco, Calif.

15 Jul 2025