Vitamin C for a cold? A good dose of Vitamin D on a sunny day? We all know that vitamins are critical for our health, but how did they get their names and when were they discovered in the first place?

American nutrition scientist Elmer McCullum conducted a variety of feed experiments with different animal populations and discovered that an “accessory” substance contained in some fats was essential to growth. That fat-soluble (脂溶的) substance became known as Vitamin “A” for “accessory.”

McCollum and others also conducted further experiments with rice-bran-derived nutrient, naming it Vitamin “B” after beriberi, which can cause heart failure and a loss of sensation in the legs and feet. Eventually, it turned out that the substance known as Vitamin B was a complex of eight water-soluble vitamins, which were each given individual names and numbered in order of discovery.

The custom of naming vitamins alphabetically in order of discovery continued. Today, four fat-soluble vitamins (A, D, E, and K) and nine water-soluble vitamins (Vitamin C and the eight B vitamins) are considered essential to human growth and health. Only one vitamin bucked the oh-so-logical naming system: Vitamin K, discovered by Danish researcher Carl Peter Henrik Dam in 1929. The substance should have been in line to be called Vitamin F given its discovery date. But Dam’s research revealed that the vitamin is essential for blood coagulation (凝固) — known as Koagulation in the German journal that published his research — and his abbreviation for the vitamin somehow stuck.

It’s been decades since the last essential vitamin — Vitamin B12 — was discovered in 1948. It now appears unlikely that scientists will ever discover a new essential vitamin. But even if there’s no Vitamin F or G in our future, that doesn’t mean nutritional discovery has stopped completely. If the golden age of vitamin discovery was an appetizer (开胃菜) of sorts, scientists are devoted to the main course — a rapidly evolving understanding of the ways food shapes our lives, one microscopic substance at a time.

There was a time when an event would not begin without a photographer. “I remember the days when event organizers would even delay a show if the photographer was running late,” says Balachandra Raju, a photographer of Sathyam Studio, a still surviving photo studio in India’s southern city of Chennai.

Photo studios are facing extinction in the digital age. But as they struggle to continue doing the business, one research project is looking at ways to preserve their legacy (遗产) by digitizing archival pictures.

The project, funded by the British Library, visited around 100 photo studios across the south Indian state of Tamil Nadu and digitized 10,000 prints. Many of the photos were taken between 1880 and 1980, and they ranged from pictures of families and famous stars to weddings and funerals. “The digital archive will be useful for those interested in history,” said Zoe E. Headley, one of the researchers. Ramesh Kumar, another researcher on the project, called it a “gold mine” for photographers. “The research we’ve done also highlights production techniques used before digital photography arrived in our cities and towns,” he said.

However, the researchers would often find old photos piled on top of one another in the storage room of a studio. “No one had bothered to clean them,” Kumar said, adding that many photos had been damaged due to the hot and wet weather in Tamil Nadu.

The owner of Nallapillai Studio in central Tamil Nadu said he spends about 20,000 rupees (￡230, $310) each month to run the studio that was founded by his great grandfather almost 150 years ago. To survive in this digital age has been a struggle. “Many customers don’t book us for special events anymore,” he said, adding that they have all got smartphones to do the job. “I’m not sure if photo studios will exist five years from now,” he said. But this is why, according to Mr Raju, this archival project is so important.

For decades, researchers and medical professionals considered sleep loss a by-product or symptom of another, more “primary” condition, such as depression or anxiety. In other words, first comes the anxiety, and then sleep loss follows. Today we know that this order can be reversed. In fact, sleep loss and anxiety, depression or other mental health conditions may feed into one another, creating a downward spiral (恶性循环) that is exceedingly difficult to break.

In a study where healthy volunteers were deprived of one night of sleep, they discovered that the activity of the prefrontal cortex (前额皮质) dropped dramatically, as measured using fMRI. Moreover, the neural activity linking the amygdala (杏仁体) and the prefrontal cortex, both the region and the circuit meant to keep our emotional reactions under control, became significantly weaker when one-night sleep is disrupted.

This damage can be so strong that it blurs (使难以区分) the lines around what people consider emotional. For example, when participants were exposed to neutral and emotional pictures (images of commuters on a train versus photographs of children crying), fMRI revealed that the amygdala responded differently to these pictures when people were well rested. But after losing a night of sleep, a person's amygdala responded strongly to both kinds of images. In other words, the threshold (阈值) for what the brain considers emotional became significantly lower when the amygdala could not work together with the prefrontal cortex. Such damaged emotional control makes us more vulnerable to anxiety and poor mood, so that even silly love songs can trigger sobs. Research also suggested changes in that brain circuit also relate to increases in blood pressure and cardiovascular disease.

Stepping back, it becomes clear that mental and emotional health rely on a delicate balance. We need to be mindful of that even a single sleepless night can therefore do damage. Inevitably, we all miss out on sleep from time to time. But our societies should critically examine structures — such as work norms and school cultures — that prevent people from getting enough rest.