If you laugh until you cry when someone touches a sensitive area on your body, you’re ticklish. Some people are so ticklish they laugh or cringe at the slightest touch or at the anticipation of being tickled. Others don’t crack a smile.

Why do some people respond to the tickle response, and others don’t?

There are a couple schools of thought on what makes someone ticklish. One theory is that being ticklish evolved as a defense mechanism to protect vulnerable areas of the body and to show submission. Another theory is that tickling encourages social bonding.

For many people, tickling is unbearable, so why do they laugh?

Scientists found being tickled stimulates your hypothalamus, the area of the brain in charge of your emotional reactions, and your fight or flight and pain responses. When you’re tickled, you may be laughing not because you’re having fun, but because you’re having an autonomic emotional response. In fact, the body movements of someone being tickled often mimic those of someone in severe pain.

Older research shows both pain and touch nerve receptors are triggered during tickling. And people laugh just as hard whether they’re being tickled by a person or by a machine.

According to researchers, there are two types of tickling:

Gargalesis is tickling that causes laughter when someone touches ticklish areas of your body repeatedly. It can’t be self-induced.

Knismesis is tickling caused by light motion on your skin that doesn’t usually bring on laughter. This type of tickling may be self-induced.

Knismesis can make you feel itchy or tingly. You may not associate it with tickling because it’s usually irritating. You could think you’re just itchy.

You may be ticklish anywhere on your body. Commonly ticklish areas include:

  • stomach
  • sides
  • armpits
  • feet
  • neck

Supporters of the theory that tickling evolved as a defense mechanism may argue these areas are ticklish because they’re the most vulnerable on your body.

Laughter doesn’t start in babies until they are around 4 months old. And they don’t start responding to tickling with laughter until around 6 months of age.

Despite the delay in laughter in response to tickling, it’s thought that babies feel the sensation of being tickled, but they don’t know where it’s coming from. They don’t initially associate the tickle sensation with the outside world or anything they see, smell, or hear.

Tickle games are common between parents and babies. They’re thought to encourage emotional and physical bonding. Still, like adults, babies may laugh when tickled, but not enjoy it. It may be fine to lightly stroke a baby’s feet or gently rub their tummy. But serious tickling should wait until a child is older and can move away easily to indicate when they’ve had enough.

Read more: 5 fun ways to make your baby laugh »

People who are extremely ticklish or who dislike the tickle sensation may struggle with physical intimacy. The lightest touch may send them into a tailspin. It’s unclear if you can permanently stifle your tickle response. Some people claim a “mind over matter” approach works. In other words, grin and bear it until you no longer laugh reflexively. You might also think about something serious when you’re being tickled.

Some scientists suggest that the same brain activity doesn’t occur if you attempt to tickle yourself. That’s most likely because you anticipate the sensation. You may be able to trick your brain by placing your hands on top of the hands of the person who’s tickling you. This allows your brain to predict the sensations and suppress the tickle response.

Autonomous sensory meridian response (ASMR) is a term used to describe physical sensations that happen because of physical, visual, and audible stimuli. It may be triggered by a person or a device. Physical sensations are described as tingling, tickling, and chills, especially in the scalp. They’re associated with a sense of peace, calm, euphoria, and well-being.

There’s not a lot of research about ASMR. One study identified common triggers used to achieve ASMR such as:

  • whispering
  • personal attention
  • crisp sounds
  • slow movements

ASMR may temporarily improve depression and chronic pain symptoms. There may be a potential connection between ASMR and synesthesia, a condition where a sensation in one sense triggers a sensation in another. More studies are needed to determine the physiological reasons for ASMR.

Laughter is often associated with fun. But in the case of tickling, that isn’t necessarily true. Some people enjoy the intimacy of tickling and the release of a good laughing session. For others, tickling is no laughing matter.

If you want to make tickling more pleasurable, consider these tips:

  • Tickle areas that are less sensitive such as the palms, top of the feet, and back of the head.
  • Tickle slowly and gently.
  • Tickle with a feather instead of your hands.
  • Don’t be rough or aggressive — keep it playful.

No matter where you fall on the ticklish spectrum, it’s important to have boundaries. Don’t force people to endure tickling, even if they’re laughing. This especially applies to children. Stop tickling at the first sign of discomfort.