We have all seen movies where right before the hero starts fighting, he cracks his knuckles and makes it look like the coolest thing in the world! But then our parents told us that you should not crack your knuckles because that weakens your grip and hand strength. But is that true? While many people do say that they experience a small loss in strength immediately after they crack their knuckles, but are their long-term effects to it? And what is the sound actually coming from?

The reason why people crack their fingers is because the evident and sharp crack noise causes a sense of relief. Many people also do it when they have done an activity that required them to work with their hands a lot like typing or sewing, giving themselves a sense of satisfaction, similar to stretching after doing hard work. That "crack" sound can make some people cringe, while others find it strangely satisfying. Cracking your knuckles is a pretty common habit, but there are a lot of misunderstandings about it. Some people do it without even thinking, others can't stand the noise, and some can't crack their knuckles at all. You might have been told as a kid that it causes arthritis or makes your fingers swell up. But those are just old wives' tales. There's a real science behind this habit, and it's more interesting than you may think.

Why Do Knuckles Make That Popping Sound?

The "crack" isn't actually bones breaking or anything bad happening to your joints. It's a normal thing called "crepitus." This just means harmless popping, snapping, or grinding sounds that come from your joints. The main reason you hear this sound is because of gas bubbles in the fluid that cushions your joints. This fluid is called synovial fluid. When you move or stretch, these tiny bubbles form and then pop, making the sound. It's totally normal and doesn't hurt you. Sometimes, especially in bigger joints like your knees, shoulders, or ankles, the sound can also happen when the stretchy tissues that connect your bones (ligaments and tendons) move slightly and then snap back into place.

After you crack your knuckles, you can't usually do it again right away. You have to wait a bit. That's because the gas bubbles in your joint fluid have already popped, and it takes a little while for them to build up again. While cracking your knuckles doesn't give you arthritis, doing it too much might cause some problems. Doctors say that cracking them too often could make your joints a little wobbly and might even make your grip weaker. Also, if the stretchy tissues in your joints keep snapping over your bones, they can get irritated and sore.

When Joint Popping Might Mean Something More

Sometimes, a pop in your joint is just like cracking your knuckles, nothing to worry about. But other times, it can be a sign of something else. As we get older, the cushiony stuff in our joints, called cartilage, can start to wear down. This cartilage helps your bones move smoothly. When it gets thin or uneven, the bones can rub together, and that can make a grinding or popping sound. This is different from the pop you get from gas bubbles. If this grinding sound happens along with pain, it could be a sign of osteoarthritis. This is a type of joint problem that's more common in older people, but younger people can get it too, especially after a joint injury. If your joints hurt, especially in the morning or after you've been sitting still for a while, feel wobbly, or are hard to move, it's a good idea to see a doctor.

In a bizarre medical case, a 28-year-old US man began seeing his pet cat Luna’s features on human faces after brain surgery. These included almond-shaped eye sockets enlarged pupils and stripes.

If Karl sees Luna first thing in the morning, he continues to see her features on human faces throughout the day, whether in person or online.

However, if he wakes up looking at a human face, he may see that person’s pupils and eye shape on other people’s faces and even on his cat.

According to a case report published in the journal Cortex, Karl experiences a form of palinopsia, in which something seen earlier persists or reappears in subsequent perception. In his case, this causes facial distortions known as prosopometamorphopsia (PMO).

How Did The Condition Begin?

Also read: Rare Canine Tooth Found In Indian Teen’s Eyelid: What Is An Ectopic Tooth?

Karl, who lives in the northeastern US, has experienced the condition for two years. It began after surgery to remove part of his right temporal lobe to treat an arteriovenous malformation (AVM), an abnormal tangle of blood vessels connecting arteries and veins that can cause bleeding in the brain.

The right temporal lobe plays an important role in face processing.

"This case of Karl seeing his cat's features in human faces and vice versa demonstrates that individual features can be pulled from memory and influence our ongoing perception," said lead author Brad Duchaine, professor and chair of psychological and brain sciences and principal investigator of the Social Perception Lab at Dartmouth.

More Than 250 People Experience Facial Distortions

Karl is not alone. According to Duchaine's lab, more than 250 people experience facial distortions. Many are mistakenly diagnosed with psychiatric problems.

"We have heard from people who have been told that they had a psychiatric problem and, in some cases, have even been put on antipsychotics, when they are in fact just having visual problems," Duchaine said.

Duchaine also cited a 1986 study published in Cortex. It described a woman who saw a poodle sitting on a passenger's lap while riding a bus. She then began seeing the poodle's face on every passenger. The woman had experienced a stroke nine months earlier.

Unlike that case, Karl sees individual facial features transferred between faces rather than entire faces.

How AI Can Help

Also read: Hours Of Sitting, Gaming And Binge-Watching OTT? Doctors Warn Of Blood Clot Risk In Young People

Duchaine used a large language model to turn a line drawing of Karl’s experience into a photorealistic image. He then worked with Karl to refine the visuals featured in the report.

AI-generated images can help researchers understand visual distortions and help patients explain their experiences to doctors, friends and family, Duchaine said, adding that he will continue working with Karl to decode more about the condition.

What Is Prosopometamorphopsia?

Prosopometamorphopsia (PMO) is a rare visual condition in which faces or facial features appear distorted due to changes in the brain's face-processing network. The term combines prosopo (Greek for face) and metamorphopsia (perceptual distortion).

People with PMO may see facial features as:

• Droopy or stretched

• Larger or smaller than normal

• Displaced or out of position

• Distorted in specific parts of the face

Two prominent subtypes are:

• Full-face PMO: The entire face appears distorted

• Hemi-PMO: One half of the face appears distorted

Most cases last days or weeks, although some persist for years. Around 75 case reports have so far been published.

Rubbing your eyes is a common habit, often triggered by itching, dryness or tiredness. However, frequent and vigorous rubbing can damage the cornea and increase the risk of keratoconus, a progressive condition that causes it to thin and bulge outward, experts warn.

World Keratoconus Day is observed every year on November 10 to raise awareness about the condition.

Early diagnosis is important to slow its progression. Frequent changes in spectacle prescriptions or deteriorating vision should prompt an eye examination.

Why Should You Avoid Rubbing Your Eyes?

Frequent or aggressive eye rubbing can put mechanical stress on the cornea, potentially weakening its structure and worsening existing eye conditions.

Speaking to HealthandMe, Dr Janhvi Mehta, Consultant Ophthalmologist, Jaslok Hospital and Research Centre, Mumbai, said, "Frequent or vigorous eye rubbing can damage the cornea, particularly by contributing to keratoconus. It can also cause corneal epithelial injury and worsen existing ocular allergy."

Repeated rubbing can:

• Contribute to corneal thinning and biomechanical weakening.
• Accelerate keratoconus in susceptible individuals.
• Cause corneal abrasions and increase the risk of infection.

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Dr Mahipal Singh Sachdev, Chairman and Managing Director, Centre for Sight Group of Hospitals, explained that excessive rubbing puts pressure on the cornea and can damage its collagen structure.

"The cornea might become thinner than usual or its shape may become uneven, leading to impaired vision. Hence, people should avoid the habit of rubbing their eyes," he told HealthandMe.

Why Are Children More At Risk?

Children with allergies, especially allergic conjunctivitis, may be more vulnerable to keratoconus because of frequent eye rubbing.

Allergies can cause persistent itching, redness, watering, and discomfort, encouraging children to rub their eyes repeatedly. The resulting mechanical stress may contribute to the development or progression of keratoconus in susceptible individuals.

The experts urged parents to watch for excessive rubbing and changes in their children's vision. Timely allergy treatment and regular eye examinations can help identify potential problems early.

Other risk factors for keratoconus include:

• Vernal keratoconjunctivitis (VKC)
• Atopic eye disease
• Family history of keratoconus
• Genetic predisposition
• Certain connective tissue disorders

However, not everyone who frequently rubs their eyes develops keratoconus.

Read More: 6 Million People In Delhi Living With Poor Vision: AIIMS Study

Why Is Keratoconus Often Diagnosed Late?

Dr Janhvi noted that keratoconus commonly begins during adolescence or early adulthood but may remain undiagnosed until vision deteriorates.

Its early symptoms can resemble common refractive errors such as myopia. Children and young adults may experience mild blurring or require frequent changes in their spectacle prescriptions, which can be mistaken for routine vision changes.

The condition can also progress gradually and initially affect only one eye, making changes harder to recognise. Routine eye examinations may not always detect early keratoconus without specialised corneal assessment, Dr. Mahipal said.

Warning signs to watch for include:

• Increasing myopia
• Progressive or irregular astigmatism
• Frequent changes in spectacle prescriptions
• Reduced visual clarity despite corrective lenses
• Ghosting, glare or double vision in one eye
• Difficulty driving at night

Increasing astigmatism despite repeated spectacle corrections is an important warning sign that warrants further evaluation.

Read More: Sudden Floaters, Flashes Or Blurred Vision? When Should You Seek Emergency Care For Retinal Changes

How Can You Prevent Corneal Damage?

Preventing excessive eye rubbing and managing its underlying causes can help reduce avoidable stress on the cornea.

1. Break the eye-rubbing habit

• Avoid pressing or massaging closed eyelids.
• Use a cold compress when your eyes itch.
• Avoid rubbing your eyes even through a towel or handkerchief.
• Keep children's fingernails short to minimise accidental injury.

2. Treat underlying allergies

If itching triggers eye rubbing, consult an ophthalmologist about appropriate treatment. Options may include topical antihistamine or mast-cell stabiliser drops, such as olopatadine or ketotifen.

Other measures include:

• Using preservative-free artificial tears for irritation
• Treating associated blepharitis or dry eye
• Avoiding prolonged use of topical steroid drops without medical supervision

3. Reduce exposure to environmental triggers

• Avoid dust, smoke and known allergens
• Wear protective glasses outdoors
• Avoid direct airflow from air conditioners.

Come Saturday morning, many people have just one thing on their mind: catching up on sleep. After a week of early mornings, office deadlines, late-night screen time and household responsibilities, the weekend feels like the perfect opportunity to stay in bed for a few extra hours. Some people even sleep until noon, believing that the extra rest will make up for all those late nights. But is it really possible to undo five days of poor sleep in just two days?

Unfortunately, the brain doesn't work that way. Sleeping longer over the weekend can certainly help you feel less tired, but it cannot completely compensate for a week of inadequate sleep.

Sleep is much more than physical rest. It is when the brain gets down to some of its most important work. Memories are processed, information gathered during the day is organised, and the brain gets an opportunity to recover from constant activity. When we repeatedly cut short our sleep, these processes can suffer.

Why Do We Feel Better After Sleeping In?

Think about how you feel after several nights of going to bed late. You may find yourself forgetting small things, struggling to concentrate during meetings or becoming unusually irritable over minor issues. These are some of the ways sleep deprivation can affect everyday functioning.

Sleeping for a few extra hours over the weekend can ease some of this fatigue. You may feel more alert and find it easier to concentrate. However, feeling refreshed is not necessarily the same as being fully recovered. Certain effects of repeated sleep restriction, particularly on attention and reaction time, can take longer to resolve.

Can Weekend Lie-ins Disturb Your Sleep Cycle?

There is another side to this weekend habit that people rarely consider. If you sleep at 11 pm during the week but stay awake until 2 or 3 am on Friday and Saturday, your body's internal clock can get disrupted.

This internal timing system, called the circadian rhythm, helps regulate when you feel sleepy and when you wake up. Large changes in sleep timings can make it harder to fall asleep on Sunday night. Before you know it, Monday morning arrives and you are back to feeling exhausted.

It becomes a familiar cycle: insufficient sleep during the week, prolonged sleep on weekends and difficulty getting back into a routine.

What Does Repeated Sleep Deprivation Do To The Brain?

One of the biggest areas affected is memory. Sleep plays an important role in consolidating information, which is why a poor night's sleep can make it harder to remember things or absorb new information the following day.

It can also affect emotional regulation. People who regularly sleep less may become more impatient, anxious or sensitive to everyday stress. Their ability to focus and make decisions may also take a hit.

Persistent sleep deprivation has also been associated with metabolic and cardiovascular problems. It is therefore important not to treat poor sleep as an unavoidable part of a demanding work schedule.

What Is A Healthier Way To Catch Up On Sleep?

Rather than depending on Saturday and Sunday to recover, try making small changes to your routine throughout the week.

• Keep a consistent schedule: Try to go to bed and wake up at roughly the same time every day.
• Don't compromise on sleep duration: Most adults need around seven to nine hours of sleep each night.
• Put your phone away before bedtime: Late-night scrolling can keep the mind stimulated and delay sleep.
• Be mindful of caffeine: That evening cup of coffee may be affecting your ability to fall asleep.
• Step outdoors in the morning: Natural daylight helps regulate the body's sleep-wake cycle.
• Pay attention to persistent tiredness: If you wake up exhausted despite getting enough sleep, speak to a doctor. Sleep disorders such as obstructive sleep apnoea may need to be ruled out.

Your brain needs rest every day, not just when the calendar says it is the weekend. Instead of treating sleep as something you can postpone and recover later, make it a non-negotiable part of your daily routine.