What are circadian rhythms?
Circadian rhythms are internal biological clocks that function on roughly 24-hour cycles, prompting daily processes and behaviors on a cellular level. Circadian rhythms play a role in everything from our wound healing and digestion to how we sleep and metabolize drugs. Directed by a master circadian clock called the suprachiasmatic nucleus, located in the hypothalamus, this central timekeeper coordinates the many peripheral molecular clocks located throughout the body. The clocks’ actions are driven by cues—formally called "zeitgebers"—that include light, food, temperature, medication, and exercise.  
 

Circadian, derived from the Latin for "about a day," refers to the light-dark timing cycles that were first studied by a French astronomer in the 1700s, who observed how a plant behaved in a dark room. Subsequent research has shown that circadian rhythms influence the actions of plants, animals, and even single-cell organisms.
 

Disruptions to our circadian rhythms from artificial light, erratic sleep and eating schedules, and other factors can cause many health issues. Circadian disruptions are linked to cardiovascular, gastrointestinal, sleep, and mental health disorders. Ongoing research seeks to better understand these relationships and unravel how to nudge our clocks back into sync.

Also, check out ... 

> Skin wounds and burns heal fastest if they occur during the day. (Read) 

> Babies don't develop a circadian rhythm right away. (Read) 

> The body's master clock has 20,000 neurons. (Read) 

> Parasites have circadian rhythms, too. (Read) 

Explore everything else we've found on Circadian Rhythms.

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A Scientific Breakthrough In Human Aging

The first signs of aging happen where you can’t see them—inside your cells. Beginning in your 30s, the mitochondria, responsible for 90% of your body’s energy, take on damage with time, and your cells slowly lose the ability to repair it. This decline wears down your energy and physical strength, leaving you feeling weak and fatigued.

Luckily, Swiss scientists have revealed a way to restore this process and support healthy aging. Mitopure®, a clinically proven longevity supplement, replaces aging mitochondria and helps to rebuild new ones, giving you your energy back. The results? Studies found participants saw energy and muscle strength increase without any changes to exercise.

Take aging into your own hands. 1440 readers can take 40% off Mitopure with code 1440HEALTH, while supplies last.

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Goose bumps 101

Goose bumps are small raised bumps that dot the skin in response to cold, fear, or sudden emotional triggers like music or art. They resemble poultry skin after the feathers have been plucked.

Formally referred to as piloerection—a nod to the muscles responsible for the hair-raising phenomenon—goose bumps occur when arrector pili muscles at the base of hair follicles contract and pull hairs erect, creating the characteristic bumps. This reflexive action in animals and birds causes their fur or feathers to stand on end. This makes them appear larger and scares off predators. It also traps a pocket of air close to the body, serving as insulation. Since humans no longer have thick hair and we wear clothes to stay warm, many scientists believe our goose bumps are an evolutionary remnant from our ancestors, like our tailbones.

In medicine, the Latin-derived term for goose bumps is cutis anserina—since “cutis” is skin and “anser” is goose. Worldwide, different cultures and languages have additional terms for these bumps, some of which reference chickens, ducks, and even snails.

Also, check out ... 

> Charles Darwin studied goose bumps by scaring zoo animals in London with a stuffed snake. (Read) 

> Some of us can actually control our goose bumps. (Read) 

> Humans accurately detect their goose bumps only one-third of the time. (Read)

> Watch how music gives some of us the chills. (Watch) 

Explore everything else we've found on Goose Bumps.

An introduction to allergies

Allergies are an overreaction of the body’s immune system to typically harmless foreign substances called allergens. Some of the most common allergens include pollen, food, household dust, pet dander, and mold. Over 100 million Americans suffer from allergies, with a price tag of more than $27B annually in combined medical and societal costs. 

Allergy symptoms occur when immune system defenders called immunoglobulin E (IgE) antibodies mistakenly label an allergen as a threat and bind to it. This leads to actions including the release of a chemical called histamine and the development of allergy symptoms, such as rashes, sneezing, swelling, or a life-threatening reaction called anaphylaxis. Symptoms can arise within minutes to hours after exposure to an allergen.

Allergies now affect more than 20% of the world’s population. Strict avoidance of allergens remains the primary way to prevent reactions, followed by epinephrine injection and emergency care if a severe reaction occurs. However, researchers and policymakers have also been finding new ways to help navigate allergies, including developing the first-ever peanut allergy treatment and issuing new guidance that encourages earlier life exposure to certain potential allergens.

Also, check out ... 

> Zoo animals have developed allergies, too. (Read)

> Tick bites can fuel an allergy to a sugar molecule in red meat. (Read)

> Kids often grow out of allergies to eggs and milk. (Listen)

> Adults are developing food allergies they didn't have as children. (Read)

Explore everything else we've found on Allergies.

 Medical Developments Spotlight 

We love spending time learning about the latest medical breakthroughs and spotlighting research that piques our interest, may influence future research directions, or inform healthcare conversations. Here's what we found this week.

> Why the common cold makes some of us sicker than others

Yale News | Karen Guzman. A new study drills down into why some of us are hit harder by rhinovirus than others. Scientists created a nose-in-a-dish, infected it with the common cold virus, and analyzed how thousands of nasal airway cells responded to the infection. (Read) 

> Alzheimer’s drug shows promise for treating sickle cell anemia 

University of Zurich. A small study found that both the number and duration of hospitalizations decreased among those who were trialing the Alzheimer's drug memantine for treatment of sickle cell anemia. A follow-up study is planned. (Read) 

> Federal data suggests US overdose deaths dropped for much of 2025

AP News | Mike Stobbe. Overdose death numbers have been trending downward for more than two years, but the decline appears to be slowing. The death toll is also still higher than it was before the COVID-19 pandemic. (Read)

In partnership with Timeline

Is Cellular Health The New Gut Health?

You’ve heard the mitochondria are the "powerhouses of your cells." Did you know these cellular structures also act as regulators of health as you age? But over time, your mitochondria's efficiency wanes, contributing to aging and risk of chronic disease.

Meet Mitopure®, a powerful healthy aging solution shown in clinical studies to significantly increase cellular energy and muscle strength, starting in as little as two months. Even better? The improvements were achieved without any change in exercise. Start your journey to more energy and stronger muscles today. 1440 readers get 40% off with code 1440HEALTH, while supplies last.

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Best of the Week

We curate hundreds of resources into 1440 Topics each week. Here are some of our favorites from the world of health and medicine.

> An app called "Are You Dead" is climbing the charts.

> Imagine a vaccine delivered via beer.

> Scientists are making progress with regrowing human teeth.

> This is what happens in your body when you're sick.

> Jellyfish sleep like humans, even though they lack brains.

> See what disability in America looks like.

> Color blindness hides a key warning sign of bladder cancer.

> Why the flu is so bad this year.

> Survey: 20% of young Nigerian kids have been exposed to skin lighteners.

>Naked mole rats' death-defying powers may further human stroke research.

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