HEADACHE, ARE YOU GETTING ENOUGH SLEEP?

 

A poor night's sleep leaves us tired and foggy. But if you've also noticed a dull ache creeping across your forehead or a throbbing pain behind one eye after a rough night, you're not imagining things. Sleep and headaches are closely connected, and understanding that link is the first step toward waking up pain free. Both too little sleep and too much sleep can trigger headaches. Tension headaches and migraines have different causes, symptoms, and treatments. Small, consistent changes to your sleep routine often prevent headaches before they even start. A headache that comes on suddenly, feels unusually severe, or comes with other symptoms deserves a call to your doctor.

 

 Migraine or Tension Headache?

Not all headaches are the same, and figuring out which type you're dealing with can help you treat it more effectively.

·        Migraine: Often felt on just one side of the head, migraines can last anywhere from a few hours to several days. They frequently bring nausea, sensitivity to light and sound, and sometimes vomiting. Some people also experience an "aura," such as flashing lights or tingling sensations, shortly before the pain begins.

·        Tension headache: This is the more common type, producing a mild to moderate pressure or tightness across the top, sides, and back of the head, almost like a tight band. Unlike migraines, tension headaches usually aren't made worse by light or noise.

 

 The Science: Why Skipping Sleep Triggers Pain

While we sleep, our brain and body aren't simply "switched off." Our body produces proteins during deep sleep that help regulate and suppress pain signals. When sleep gets cut short, production of these proteins drops, and our pain threshold falls along with it. Researchers have also found that even a single night of poor sleep can raise inflammatory markers and lower pain tolerance within about 24 hours, which explains why one bad night is sometimes all it takes to bring on a headache.

There's a second piece to the puzzle as well. During deep sleep, the brain relies on a natural cleanup system, sometimes called the glymphatic system, to clear out waste products that build up during the day. Cutting sleep short interferes with this process, which some researchers believe contributes to next-day headaches.

 

How Much Sleep Do You Actually Need?

Most healthy adults function best on seven to nine hours of sleep a night. As we get older, that number narrows slightly:

·        Adults 18 to 647 to 9 hours per night

·        Adults 65 and older7 to 8 hours per night

Quality matters just as much as quantity. Frequent nighttime waking or restless, fragmented sleep can leave you with headache-prone mornings even if you technically spent eight hours in bed.

 

The "Weekend Headache": Why Sleeping In Can Backfire

Here's a twist many people don't expect: oversleeping can trigger headaches just as easily as sleep deprivation. This is common enough to have its own nickname, the "weekend headache," and it tends to strike people who run short on sleep during the work week and then try to make up for it by sleeping in on Saturday or Sunday.

A few things seem to be going on at once. Sleeping in disrupts your normal serotonin rhythm, the same brain chemical involved in regulating your sleep-wake cycle and pain sensitivity. Lying still for extra hours can leave neck and shoulder muscles stiff and tense. The fix is simpler than it sounds: try to wake up within about an hour of your usual time, even on days off. If you're genuinely behind on sleep, an earlier bedtime does more good than a later wake-up time.

 

Sleep Apnea can be the Real Culprit

If you regularly wake up with a headache that fades within an hour or two, it's worth considering whether something is interrupting your sleep without you fully realizing it. Sleep apnea, a condition in which breathing repeatedly stops and starts during the night, is linked to morning headaches in a notable share of people who have it. The repeated drops in oxygen and disrupted sleep cycles are thought to be the cause. Sleep apnea becomes more common with age, and often shows up alongside snoring, gasping during sleep, or daytime drowsiness. Please discuss this with your doctor. A sleep study or polysomnography can help diagnosing it and some lifestyle modifications and a CPAP (Continuous Positive Airway Pressure) can add several peaceful years to your life.

 

Treating a Headache Once It Starts

If a headache does strike, several options can bring relief. For tension headaches, over-the-counter pain relievers such as ibuprofen, aspirin, or naproxen are typically effective. For recurring tension headaches, a doctor may suggest preventive options.

Migraines tend to need a more targeted approach. Options range from over-the-counter pain relievers for milder attacks to prescription medications such as triptans, which work by narrowing blood vessels and interrupting pain pathways in the brain. For migraines that last longer or come with severe nausea, a doctor might recommend other prescription options or anti-nausea medication. Preventive treatments, including certain blood pressure medications, antidepressants, and monthly injectable medications, are also available for people who experience frequent migraine attacks. One of the biggest changes in treatment has come from understanding a substance called calcitonin gene-related peptide, or CGRP. This naturally occurring chemical messenger plays a role in the pain pathways involved in migraine. Newer medications target either CGRP itself or the receptor it acts on, helping interrupt those signals.

 

Because many of these headache medications can interact with other prescriptions or existing health conditions, it's always worth checking with your doctor before starting something new, especially if you're already taking regular medication for another condition – Diabetes, Hypertension etc.

Surgery for Migraine

Now migraine is also being treated surgically by Plastic Surgeons practicing peripheral nerve surgery. In intractable cases the results of surgery are good. The goal of migraine surgery is to reduce or eliminate headache frequency, duration and pain. Migraines can be associated with compression and irritation of sensory nerves and vessels around the head. When these compression points are released during surgery, the severity of migraines may decrease or one may not experience further migraines.

Sites of nerve compression are also known as trigger points. There can be several trigger points depending on the symptoms. The most common and main trigger sites are frontal (pain above the eyes and/or forehead), temporal (pain over the temples), rhinogenic (pain inside your nose that can extend to behind the eyes), occipital (pain on the back of head that can radiate across the skull to the eyes or behind the eyes). Individual nerves can be freed from constricting confines, and even cut and capped to free the patient of intractable pain.

 

Home Remedies Worth Trying

·        Rehydrate: Even mild dehydration is a well-documented headache trigger, and simply drinking a glass or two of water can sometimes ease symptoms within an hour or so.

·        Suppliment magnesium: Studies suggest people prone to frequent headaches often run low on magnesium. Leafy greens, almonds, and whole grains are good dietary sources, and a supplement may help too, though it's best to check with your doctor first, especially if you take other medications.

·        Try a compress: A cold compress on the forehead or a warm one on the back of the neck can both ease tension and throbbing pain, depending on what feels better for you. Rest in a quiet, dark room. This is especially helpful for migraines, which are often worsened by light and noise.

·        Explore acupuncture or massage: Both have shown promise for reducing headache frequency and easing muscle tension in the neck and shoulders. But approach only a qualified personnel.

·        Cognitive behavioral therapy: CBT can help break the cycle of stress and poor sleep that often feeds recurring headaches.

 

The Right Way to Nap

A short nap can genuinely take the edge off a headache, especially one brought on by fatigue. But naps can just as easily cause a headache if we are not careful. Napping too long can trigger the same oversleeping effects described earlier, and dozing off in an awkward position, such as slumped in a recliner or on the couch without proper neck support, can leave one with a stiff neck and tension headache on waking up. To get the benefit without the downside, we should keep naps to 20 or 30 minutes, use a pillow that keeps our head and neck level rather than tilted, and avoid napping too late in the afternoon, since that can make it harder to fall asleep that night.

 

Building Better Sleep Habits to Prevent Headaches

1. Keep a consistent schedule. Go to bed and wake up at roughly the same time every day, weekends included.

2. Get daytime light exposure. Natural light during the day helps anchor your body's internal clock.

3. Ease off screens before bed. The blue light from phones and tablets can delay your body's natural release of melatonin, making it harder to fall and stay asleep.

 4. Watch your evening caffeine and alcohol. Both can fragment your sleep, and alcohol in particular tends to disrupt the deeper stages of sleep later in the night.

5. Keep the bedroom cool and dark. A room temperature around 65 to 68°F (18 to 20°C) is generally considered ideal for sleep.

6. Eat lightly in the evening. A heavy meal close to bedtime can cause indigestion that disrupts sleep.

7. Exercise earlier in the day. Regular activity supports good sleep, but exercising too close to bedtime can be overly stimulating. Aim to finish at least three hours before bed.

8. Build a wind-down routine. Reading, light stretching, or a warm bath can signal to your body that it's time to rest.

9. Taper fluids before bed. Drink enough during the day, but ease off in the hour or two before sleep to avoid nighttime bathroom trips.

10. Don't force it. If you're not sleepy at your usual bedtime, it's fine to wait 20 to 30 minutes rather than lying awake and getting frustrated.

 

 When is medical attention required?

Most sleep-related headaches are uncomfortable but harmless, and they tend to fade once our sleep gets back on track. That said, certain warning signs deserve prompt medical attention:

1.      A sudden, severe headache unlike any you've had before

2.      A headache accompanied by confusion, slurred speech, vision changes, weakness, or fever

3.      Headaches that regularly wake you from sleep

4.      A noticeable change in your usual headache pattern, especially after age 50

5.      Headaches paired with loud snoring, gasping, or excessive daytime sleepiness, which may point to sleep apnea  

 

 

The relationship between sleep and headaches runs in both directions: poor sleep brings on headaches, and headaches make it harder to sleep well. The good news is that this cycle is very often within our control. Keeping a steady sleep schedule, staying hydrated, managing stress, and paying attention to how our body responds to naps and weekend sleep-ins can go a long way toward keeping headaches at bay, and toward making sure we wake up feeling fresh again.

REMEMBERING PROF. G.P. AGARWAL BY HIS BEDSIDE TEACHING

 

Prof. Giridhar Prasad Agarwal was our teacher in Surgery in King George's Medical College in Lucknow. He was Professor in charge of experiment surgery and was a very kind hearted soul. He was a dog lover, and not only his own pet dog, but even the ones brought for experimental surgery were treated with great care like guests in true Lucknavi style. Though in those days Good Laboratory Practices and Institutional Animal Care and Ethics committees were in their infancy, but Prof. Agarwal was far ahead of his time. He would emphasize to us that dogs experience pain, fear, and attachment. This created a high moral duty on our part to protect them from unnecessary harm and treat them with kindness. He would critically analyze the necessity of an animal experiment, ensure pain free procedure with sedation, anaesthesia and analgesics, and insist on good postoperative care and painless animal sacrifice if required.

 

However, if a surgical resident's thesis did not involve experimental surgery, this aspect of Prof. Agarwal always remained hidden from them. When Prof. P. C. Dubey was our Head of the Department, and Prof. R. P. Sahi was No. 2, Prof. G. P. Agarwal was No. 3 and easily the most benign in the surgical stratosphere. Always smiling, and always very loving, a rotation in his unit was a celebration. Dr. I.D. Sharma was the lecturer designated to his unit, and the latter enjoyed complete independence in running his breast unit. In fact, when Dr. Sharma needed space for his newly installed Thermography unit, Prof. Agarwal created a nice and cozy place for the same in Experimental Surgery building. He always encouraged Dr. Sharma to follow his passion and helped him in every possible way. I have, in the past, written about Prof. I.D. Sharma. In case you have missed it please click: https://surajitbrainwaves.blogspot.com/2026/04/remembering-prof-i-d-sharma-early.html

 

Prof. G. P. Agarwal's rounds would start from the General wards of Surgery, where he would often stop to conduct bedside teaching of the undergraduate students, who were since morning being taught by his residents. He would briefly examine the patient, while he is being told the history, and then start teaching, as if it was a prepared lecture. The two hallmarks of his bedside teaching were his bedside manners and his insistence on correct elicitation of physical signs. He could make a roadside beggar feel like a VIP by his immaculate manners and kind and respectful words. Every patient considered him to be their family member. Greeting the patient, seeking permission before examining them, comforting them from time to time, sharing a joke with them, admonishing them, every thing about that conversation was picture perfect and a life lesson for the students and residents. He would never forget to greet the nurses and thank them at the end of the rounds. As he was a food lover, many senior nurses and ward matrons would bring home cooked food or snacks for him, and we all devoured them.

 

From the General Wards we would move to the private wards and here the picture was absolutely different. Every patient was his 'bhai sahab', or 'Bhabhi ji' or 'didi' or 'beta' or 'beti'. Not only did he know them personally, but he knew everything and everyone in their family! Again snacks awaited his arrival and his surgical team was treated as his family, which has come to visit them. When these private patients were discharged and we would keep their bill in front of him, he would often scratch the amount mentioned against 'surgical fee' and write 'zero'. Naturally different patients reacted differently, some were embarrassed and insisted on paying, but he would politely refuse. Some came back with loads and loads of sweets and gifts for him and his team. I often wondered why would he refuse his surgical fee, when these people could afford. But, the answer was not so simple. Once, a jeweler returned with his wife, who was operated for cholecystectomy two weeks back and while leaving, with a lot of hesitation, pressed a set of two keys into his hands while shaking it. Prof. Agarwal said, "Lala ji, your car keys!" 'Lalaji, aapke garhi ki chabhi'.The jeweler politely said, "Sir, they are yours" 'aap hi ki hai!'  He was cementing a life long relationship with these families and with their communities, and the surgical fee was a very small price to pay. He was truly a member of their family, attending the weddings and standing in the funerals with these families. 

 

Our rounds usually never ended without refreshments and if after the rounds we were left famished then Prof. Agarwal would take all of us to Kwality, an up market restaurant in Hazratganj for coffee and cakes and pastries. To say that he was a food lover would be a huge understatement. Despite being a diabetic he loved sweets and fried snacks, and must have been the worst patient of his poor physician. He was in charge of food and catering every time not only the Department of Surgery, but any department hosted a conference in KGMC. Later Dr. R.K. Tandon joined him and the two could handle even massive conferences like the 1984 Annual Conference of Association of Surgeons of India in Lucknow.

 

I knew Prof. Agarwal personally even before joining KGMC because his daughter Neelu and I were classmates in Lucknow University. While I got selected first in AFMC and then in KGMC, Neelu got admission in B.R.D. Medical College, Gorakhpur. His son, Vivek was my wife's classmates. Unfortunately, both of them are no more with us today. I assisted Prof. Agarwal in his private practice. He lived in a luxurious campus bungalow in Shahmina Road, where the Centenary Hospital stands proudly today. His garage, a part of driveway, and one adjoining room were converted into an OT and post operative ward. We would operate hernia, hydrocele, appendectomy, cholecystectomy, ovarian tumours, hysterectomy, superficial thyroidectomy and amputations all in that O.T. The legendary Chotey Lal would assist us, and he would always tell me to closely watch the skin sutures and the dressings done by Prof.Agarwal. Chotey would tell me that this is the bit of Surgery that the patient would observe. You have to do this meticulously to make a good impression! Surgery at home naturally ended with refreshments and Mrs. Agarwal would insist on another refill even when our stomach was about to burst! After retirement he moved to his own home in Mahanagar and operated in Neera Hospital.

 

Today, I am reminded of a bedside teaching in a patient who presented with nausea. I was a Junior Resident in his team then. He took the class away from the patient to the middle of the ward where there were benches for the students and a chair and a blackboard for him. The class took 2 minutes to settle down and by that time he had planned his teaching format.

 

Prof Agarwal insisted on a detailed clinical history and a focused abdominal examination. The purpose was to rule out acute surgical emergencies like bowel obstruction or acute abdomen, and order baseline laboratory investigations, and an upper GI endoscopy as indicated. In those days we did not have ultrasound and peptic ulcer was fairly common, and still a disease being treated by surgeons. So, this is how his class went:

 

History and Physical Examination

• Symptom duration: Ask if the nausea is acute or chronic.
• Associated signs: Check for vomiting, fever, pain, or weight loss.
• Abdominal examination: Check for tenderness, distension, masses, or bowel sounds.
• Surgical history: Review past operations for potential adhesions or strictures.

 

Diagnostic Testing

• Blood tests: Order a complete blood count, electrolytes, and liver function tests.
• Imaging: Get an upright chest and abdominal X-ray to check for free air or obstruction.
• Fractional test meal: A method of examining the secretion of gastric juices; the stomach contents were sampled at intervals via a stomach tube after a test meal of gruel and an acid curve was generated. After the meal, assessments of gastric emptying, gastric acidity, pancreatic secretion, or nutrient absorption could be undertaken.
• Barium swallow/meal - Barium tests are used to help see the outline of various parts of the gastrointestinal tract. These include the oesophagus, stomach, and small intestines. 
• Endoscopy: Consider an upper GI endoscopy if symptoms are chronic or non-acute. 

 

Who demands immediate attention?

All patients presenting with nausea who exhibit signs of

     ·        a surgical abdomen
·        hemodynamic instability
·        severe metabolic depletion

require immediate admission. Admitting these patients promptly is vital to prevent life-threatening complications like organ perforation, septic shock, or irreversible tissue ischemia.

The specific patient profiles requiring immediate admission, along with the physiological reasons why, include: 

1. Patients with Signs of Peritonitis (Acute Abdomen)

• Clinical Presentation: Severe, localized, or generalized abdominal pain that worsens with the slightest movement, accompanied by involuntary guarding, rigidity ("board-like" abdomen), and rebound tenderness. 
• Why Admission is required: These signs indicate inflammation of the peritoneal lining, usually caused by a perforated hollow organ (e.g., a perforated peptic ulcer, ruptured appendix, or diverticulitis). Immediate admission allows for emergency surgery to patch the perforation and wash out the peritoneal cavity before overwhelming sepsis develops. 

2. Patients with Hemodynamic Instability or Shock

• Clinical Presentation: Nausea accompanied by tachycardia (HR > 100 bpm), hypotension (SBP < 90 mmHg), tachypnea, cold/clammy skin, or altered mental status. 
• Why Admission is required: The patient is experiencing circulatory failure. In a surgical setting, this points toward septic shock (from a severe intra-abdominal infection like ascending cholangitis) or hemorrhagic shock (from conditions like a ruptured abdominal aortic aneurysm or ruptured ectopic pregnancy). They require immediate intensive monitoring, aggressive intravenous resuscitation, and definitive source control. 

3. Patients with Complete Bowel Obstruction (Strangulation Risk)

• Clinical Presentation: Nausea and bilious or fecal vomiting paired with abdominal distension, severe cramping pain, and obstipation, which is inability to pass both stool and flatus. 
• Why Admission is required: A mechanical blockage (from adhesions, hernias, or tumors) halts the normal flow of the GI tract. If left unmanaged, the intraluminal pressure can compromise the intestinal blood supply, leading to bowel ischemia, gangrene, and necrosis. Immediate admission ensures gut decompression via a nasogastric (NG) tube and monitoring for emergency surgical resection. 

4. Patients with Abnormal Vomit Content (Gastrointestinal Bleeding)

• Clinical Presentation: Nausea accompanied by vomiting frank blood or "coffee-ground" material. This is hematemesis. A history of black tarry stools is melena which suggests bleeding in upper G.I. tract. 
• Why Admission is required: This indicates active upper gastrointestinal bleeding from causes such as a bleeding peptic ulcer or a Mallory-Weiss tear. Admission is mandatory for active resuscitation, blood type matching, and an urgent diagnostic/therapeutic upper GI endoscopy to achieve hemostasis.

5. Patients with Severe Dehydration and Metabolic Derangement

• Clinical Presentation: Persistent vomiting resulting in, minimal to no urine output, extreme lethargy, and labs showing profound hypokalemia, hyponatremia, or metabolic alkalosis.

• Why Admission is required: Severe electrolyte imbalances can trigger lethal cardiac arrhythmias, and severe hypovolemia can result in acute renal failure (ARF) The patient requires inpatient IV fluid resuscitation and structured, continuous electrolyte replacement.

 

Causes of Nausea

Surgical Causes

• Gastroparesis: Delayed stomach emptying often linked to prior vagus nerve injury during abdominal surgery.
• Bowel Obstruction: Partial or intermittent blockages from scar tissue or adhesions after past operations.
• Dumping Syndrome: Rapid gastric emptying occurring after gastro-jejunostomy.
• Post-Surgical Retained Foreign Body: Rare surgical complications leading to chronic irritation and nausea.

 

Non-Surgical Causes

• Medications: Side effects from chemotherapy, opioids, antibiotics, or nonsteroidal anti-inflammatory drugs.
• Metabolic Disorders: Conditions like uremia, diabetic ketoacidosis, or thyroid imbalances.
• Neurological Conditions: Migraines, increased intracranial pressure, or vestibular disorders.
• Gastrointestinal Disease: Peptic ulcer disease, gastroesophageal reflux disease, or chronic hepatitis. 
• Pregnancy: Morning sickness is common in first trimester of pregnancy - between 6 to 14 weeks it is most frequent - almost 70% ladies have it.

 

Psychological Causes

• Anxiety and Depression: Mental health conditions that strongly alter gut motility and brain-gut signaling.
• Chronic Nausea and Vomiting Syndrome: A functional GI disorder where nausea occurs without physical blockage.
• Cannabinoid Hyperemesis Syndrome: Nausea linked to regular cannabis use, often relieved by hot showers.
• Eating Disorders: Conditions like anorexia or bulimia nervosa that cause persistent gastrointestinal distress. 

 

That is how the bedside teaching of Prof. G.P. Agarwal ended. Teachers like Prof. Agarwal never taught from books, but from their experience. They would revise the important bits again and again, ask every person of that small batch which was attending the bedside teaching, and ensure that the even the last in the class has understood the subject. A patient and unthreatening approach in the morning would be followed up by the evening teaching by his Senior Resident revising the same lesson with the same batch. This is what made our bedside teachings matchless!

GUARDING CHILDHOOD FROM THE NET WOLF

 

Parents today often reach for the smartphone the way earlier generations reached for a rattle or a storybook. A cricket match is on television, a kitty party is in full swing, work emails demand attention—and the glowing rectangle is handed over. Babies are not born with an instinct to clutch a phone. Adults place it in their hands. In nuclear families the device has quietly taken the place of grandparents, the cartoon channel, the neighbourhood nanny, and sometimes even the parents themselves. The arrangement feels convenient—until the consequences become visible.

 

Children no longer “go online.” They live there. The internet is their playground, corridor, classroom, gossip bench, talent show, shopping arcade and emotional support system all at once. It is not a destination; it is habitat. Yet this habitat answers to no one—not parents, not teachers, not the law in any consistent way. Platforms host children’s behaviour and, more importantly, shape it. 

 

Children arrive in this world without suspicion. They treat “likes” as genuine approval, virality as natural weather, popularity as merit, and an unfriend or thumbs-down as personal rejection. A “friend” is not the same as a follower; a “trend” is not discovery but an instruction wearing mascara. The online environment arrives pre-arranged by entities whose motives are commercial at best and extractive at worst. Children lack the maturity to ask the crucial questions: Who gains? Who profits when I feel anxious and return compulsively to the feed?

 

That missing skill can be called motive literacy. The ability to recognise that the medium which speaks in the accent of friendship still bills in the language of attention and data extraction is not present in innocent children. Parents themselves are only beginning to grasp this. Once they do, the harder task remains: teaching it to children who have never known a world without constant connectivity.

 

Teaching motive literacy to children is vital. It means helping children notice that the online world is rarely neutral. Platforms, creators, and algorithms speak in the language of friendship, fun, and discovery while operating on commercial motives: capturing attention, collecting data, driving engagement, and generating profit. The core habit is learning to ask, calmly and repeatedly: Who made this? Why? Who gains? What does this want from me? This skill does not require turning children into cynics. It builds the same healthy suspicion we once taught about strangers, advertising, or playground politics—only applied to the digital habitat they now inhabit.

 

The disappearance of traditional storytelling compounds the problem. In earlier joint families, grandparents transmitted civilizational memory through the Ramayana, the Mahabharata, the Panchatantra and Aesop’s fables. Those stories carried values, warnings and moral complexity. In many nuclear households that informal curriculum has thinned. In its place stands an algorithm optimized for engagement, not wisdom. Parents sometimes believe screens insulate children from peer cruelty, caste prejudice or class snobbery. The discrimination has not vanished; it has simply become faceless. A child can still be tormented—yet suffers alone, and by the time adults notice, the damage is often advanced.

 

Once there was a schoolyard bully who could be confronted by teachers or parents. Today’s cyber bully lives in a space that is difficult to police and almost impossible to hold accountable. Falsehoods travel faster than corrections. Manufactured hunger for validation keeps young minds returning to the same platforms that intensify their anxiety. The medium is rarely held responsible.

 

None of this is an argument for digital abstinence. The internet is too deeply woven into education, creativity and social life to be simply switched off. The task is deliberate cultivation of awareness. Motive literacy can be taught the same way we once taught children to cross a busy road: by explaining the hidden rules of the environment, modelling scepticism, and setting boundaries that grow with the child’s capacity. Families can restore some of the narrative richness that screens displaced—reading together, recounting family stories, discussing the motives behind the content children consume. Schools can treat digital citizenship as seriously as physical safety. Platforms can be pressed, through regulation and public pressure, to design for developmental reality rather than pure engagement metrics.

 

Childhood is not merely a phase to be managed with electronic pacifiers. It is the period in which suspicion, judgment and resilience are formed. When the playground turns into a casino before children can recognise the difference, the loss is not only individual; it is cultural. The net wolf is already at the door. The question is whether adults will keep handing it the key, or finally learn to guard the threshold.