1. How Do Blind People Dream?
Tell your child: A recent study has shown that people who are born blind, having never experienced sight, don't have a clear concept of colors. As a result, blind individuals cannot perceive colors in their dreams. Instead, they experience actions or sensory experiences related to their real-world interactions.
What you should know: Some individuals are born with physical disabilities, and those born blind have never seen anything. The question arises: if they can't see, do they dream when they sleep? Research indicates that they do dream, but their dreams don't include images. Instead, their dreams are filled with other senses such as smell, touch, and hearing. Their dreams are more sensory and varied compared to sighted people, who typically dream in images (mostly in black and white). Blind individuals can still dream in images, but these fade over time, replaced by other sensory experiences. It's not necessary to overwhelm children with too much detail on this topic, as it might be difficult for them to fully understand. Instead, provide additional related information to spark their curiosity.


2. Why Do People Sleep with Their Eyes Closed?
Explain to your child: Closing our eyes while sleeping is like winding up a clock—it helps our body recognize the difference between day and night. First, when we close our eyes, they’re shielded from light, dust, and other distractions. Second, keeping our eyes closed triggers the production of melatonin, a hormone that makes us feel sleepy.
What you should know: Melatonin is produced in the brain, but it’s also created in the retina of our eyes. Light exposure can block melatonin production in the retina. Some people even sleep with one eye partially open, or like the legendary General Zhang Fei, sleep with their eyes wide open. This can happen when the brain, not the retina, produces enough melatonin. Studies of birds have shown that our eyes act as a biological clock. Some fish can sleep with their eyes open, ducks sleep with one eye open, and dolphins sleep in a unique way, with only one hemisphere of their brain resting at a time. While this can be a tricky concept, simplifying it for a child can help them grasp it more easily.


3. Why Do People Grind Their Teeth While Sleeping?
Explain to your child: Teeth grinding, or bruxism, is a sleep disorder where a person clenches their teeth tightly, which can create pressure on the teeth and produce a grinding sound. While teeth grinding is a common habit, grinding them during sleep is considered a medical condition. If this happens frequently, it can cause discomfort for anyone sleeping nearby, and may even lead to damage to your teeth and jaw, or cause more serious complications.
What you should know: Teeth grinding may happen unconsciously, either while awake or during sleep. This condition can be linked to various mental health disorders, such as Parkinson's disease, dementia, acid reflux, seizures, night terrors, sleep apnea, or attention deficit hyperactivity disorder (ADHD). It’s a complex subject, even for adults, but explaining it simply to your child can help them understand the issue better.


4. Why Do We Dream While Sleeping?
Explain to your child: Dreaming is when our mind experiences vivid images, sounds, and intense emotions during sleep. This phenomenon happens not only in humans but also in most birds and mammals. Dreams can be divided into two types: ordinary dreams and lucid dreams.
What you should know: Sleep is not just about lying down and resting until morning. Our body undergoes complex changes as we sleep. A sleep cycle includes four stages: light sleep, deep sleep, and REM (Rapid Eye Movement) sleep. Each cycle lasts about 90 minutes, and throughout a 7-8 hour night, an average person will experience 4-6 cycles. Even today, the exact reasons for dreaming remain mysterious, and it is an intriguing topic that continues to attract scientific interest. Every person has a unique brain, different life circumstances, relationships, routines, and sleep patterns. All of these factors influence the nature of our dreams, including spiritual dreams, dreams that reflect deep thoughts, or even dreams that may have no particular meaning. This is a complex topic even for adults, but by simplifying the explanation, children can better grasp the idea.


5. Why Do We Feel Dizzy When Looking Down From Heights?
Explain to your child: When we are high up, the pressure from the air and the wind, combined with the visual stimuli of looking down, can affect the balance system in the ear. These factors temporarily disrupt our sense of balance, causing dizziness, and sometimes even nausea, similar to motion sickness.
What you should know: The cerebellum controls our balance. Strong stimuli, such as those experienced when looking from a high place, reach the cerebral cortex – the brain's control center – and affect the cerebellum through visual and auditory signals. This causes a series of bioelectric activities that briefly interfere with the cerebellum's function, leading to dizziness. So why do we experience this when looking down from a building but not when on a mountain? It's simple. A building has a clear contrast in height compared to its surroundings, creating a stronger stimulus. On the other hand, a mountain, even though much higher, has a gradual slope, and the difference in height is not as noticeable, so it doesn't trigger as strong a reaction. It's best to use a concrete example to help children understand and apply this concept to other situations.


6. Why Do We Experience Sleep Paralysis?
Explain to your child: Sleep paralysis, also known as sleep atonia, occurs when you feel unable to move your body even though you're awake. This happens when your body transitions between sleep and wakefulness. During this time, you may feel stuck for a few seconds or even a few minutes. Sleep paralysis typically occurs during the REM (Rapid Eye Movement) phase of sleep when you are still conscious.
What you should know: Many people believe that sleep paralysis is caused by supernatural forces, like spirits or demons. However, experts have explained it through science. Sleep paralysis happens when a part of the REM sleep phase occurs while you are still awake. During REM, the brain is highly active and dreams occur. To prevent you from accidentally harming yourself during dreams, the body becomes temporarily paralyzed, except for eye movements and muscles used for breathing. It's best to explain the topic in a simpler way to kids, so they won't be overwhelmed with details. You can also share some fun facts about the topic to make them more interested in learning.


7. Why do we feel sleepy?
Explain to the child: Sleep plays an essential role in human life, but we often don't fully understand what causes our sleepiness or the mechanism behind it in the brain. Some studies in mice have shown that star-shaped glial cells in the brain trigger sleepiness by releasing a neurotransmitter that promotes sleep, which is inhibited by caffeine.
What you need to know: Scientists also point out that adenosine is a key factor in creating sleep pressure. This chemical builds up in the brain while you're awake, later triggering brain activity patterns unique to sleep. Unlike other nerve cells, these star-shaped cells do not send out electrical signals, and they are considered basic support cells. Overall, sleep issues stem from various causes, such as jet lag, night shifts, or working outside your body's natural sleep rhythm. This is a complex topic even for adults, but if you explain it to the child in simple terms, they can grasp the concept more easily.


8. How does the ear determine the direction of a sound?
Explain to the child: The human ear is composed of three main parts: the outer ear, the middle ear, and the inner ear. The ability to pinpoint the direction of sound improves when both ears receive signals. One key factor in identifying where a sound is coming from is the time difference between the two ears. For example, if the sound originates from the right side, the sound wave reaches the right ear a fraction of a second earlier than the left ear. Even a time difference of just 0.03 seconds can help the brain detect the direction of the sound.
What you need to know: Psychological experiments have shown that if only one ear receives sound from two different sources, and both sources are equal in volume and distance but coming from different directions, the brain perceives both sounds the same way. In this case, it’s impossible to identify the direction of the sound. However, when both ears detect the sound, the brain can make a clear determination. The first clue is the time difference between the sounds reaching each ear. For example, if the sound comes from the right, it reaches the right ear slightly earlier than the left. A stopwatch can measure this difference, and even a small gap of 0.03 seconds allows us to determine the direction. Another important clue is the difference in sound intensity. If the sound is louder in one ear, it helps pinpoint whether the source is to the left or right. However, young children may not fully grasp these concepts. The best way to explain this to them is by using simple examples they can relate to, making it easier for them to understand and apply this logic to other situations, like how to imagine the sounds from different planets.


9. Why do ears fold down when a plane takes off or lands?
Explain to the child: The reason is simple: when an airplane takes off or lands, it needs to raise its nose higher than its tail. For example, during takeoff, the front of the plane must rise first, while during landing, the rear wheels need to touch the runway first to help balance the aircraft. The ear folds down to allow the airflow to help lift the plane off the ground or ease its descent, ensuring a safe and smooth takeoff or landing. The basic principle here is that thrust is needed to lift the plane into the air.
What you need to know: The ear ringing that occurs when flying is due to the pressure difference between the middle ear and the surrounding environment. This causes the eardrum to vibrate abnormally. The Eustachian tube, which connects the middle ear to the throat, helps regulate and balance this pressure. However, during takeoff and landing, the rapid changes in air pressure often overwhelm the Eustachian tube, resulting in the sensation of blocked ears. Swallowing or yawning helps open the Eustachian tube, allowing air to flow into the middle ear and balance the pressure. While this may be a complex concept for adults, explaining it simply can help children better understand the situation.


10. Why do we feel like everything is spinning when we're dizzy?
Explain to the child: Imagine you’re on an airplane during a storm. The plane bounces up and down, but your eyes see the inside of the plane without noticing any movement. This can create a dizzy feeling. Dizziness occurs when the central nervous system receives mixed signals from five different systems in the body.
What you need to know: Dizziness happens when the body loses its sense of balance in space. We maintain balance through five systems: the inner ear detects the motion of the head up and down or side to side; the eyes track movement in space; the body senses gravity and pressure against the ground; muscles and joints track movement in the limbs and torso. The central nervous system processes all these signals to help us understand where we are in space. Dizziness arises when these signals are not synchronized. You don’t need to give too many technical details to a child, as they may find it overwhelming. Instead, using simple examples around the topic will make it more interesting and understandable for them.


