Winter melon cooling hack goes viral but experts warn to be careful

Recently, an internet meme about cuddling with winter melons to cool down during sleep as a cheap alternative to air conditioners has swept Chinese social media platforms, but experts warn the fruit may come with a risk of cold-related illnesses, and they could even rupture during the night.

Winter melons are made up of more than 95 percent water, making them similar to water-filled cooling pillows. Their outer gourd generally runs 3 to 5 C cooler than room temperature. When pressed against the human body, they can draw away surface heat and deliver cooling effects.

In the meme, a 7.5-kilogram giant winter melon is jokingly described as a portable, zero-electricity, quiet air conditioner.

This cooling hack is no modern-day invention. Ancient Chinese people relied on the very same trick to get through sweltering summer nights, a technique recorded in historical documents.

Ding Yiyun, a physician from the psychosomatic medicine department of Dongfang Hospital, Beijing University of Chinese Medicine, told Beijing Daily that sleeping with a winter melon mainly works for people suffering from insomnia triggered by summer heat or those burdened with anxiety or heavy stress.

However, people whose constitutions are susceptible to cold ought not follow this online trend to avoid cold-related health issues. Ding suggests hugging it 10 to 20 minutes before sleep instead of all night and cycling out the melon after use to avoid bacteria buildup.

Outside of such medical recommendations, some people have already reported mishaps with the vegetable. Several people have described waking up in the night to find their melons burst open, with rotten, foul-smelling juice splattered all over their bed sheets and floors.

A netizen in Hubei province posted a video online of the "disaster", saying that she had to throw everything away. Another one commented that "the smell is torturing".

Ao Qingyan, a senior agronomist at the Chengdu Academy of Agriculture and Forestry Sciences, told Sichuan-based media outlet Fengmian News that when the melon is held against the skin overnight, heat from the body combines with heat from the confined space beneath bedding, essentially turning the melon into a temperature incubator.

In warm, damp conditions, microbes multiply rapidly and break down sugars and organic substances inside the melon, generating carbon dioxide and other gases. The airtight gourd traps these gases and allows internal pressure to build up.

Still, as netizens put it, picking up a big winter melon is a bargain. After you test the cooling trick for yourself, cook it into soups and dishes. It makes a refreshing summer food and avoids wasting the produce.

Boiling it into a soup also gives a cooling effect, with no risk of "explosion".