It puzzled Emily when she was aware of something wrong. She tripped upon men’s clothing “hidden” around her house.

The 38-year-old woman says, at the beginning, she was confused to see quite a few photographs in her phone that she did not remember taking. She was the subject but something was different. Her friends started falling away and she did not know why. Her long-term relationship with her boy friend also ended suddenly.

Now she knows those men’s clothing belonged to one of her “alternatives” and the same person was responsible for her closest friends’ leaving her.

In an interview, Emily said she was not allowed to name “the man” who takes over her body. She was not allowed to name any of her six alternative persons. She said, “I am aware that they are not real people, not physical people. They exist in an imaginative world. However, all those alternatives should be treated with dignity and respect.”

Emily has what’s called Dissociative Identity Disorder （ DID 分 离 性 身 份 识 别 障 碍 ） , a condition characterized by the presence of two or more split personalities that have power over a person’s behaviour.

Her condition resulted from a car accident five years ago. It was August, 2012, when her vehicle broke down on the side of the road. A speeding driver crashed into her car. She wasn’t physically injured but she suffered a mental condition caused by severe brain injury. Shortly after that, she discovered she wasn’t alone inside her head. Switching between personalities happens frequently but there is no real pattern. It can be weeks between incidents then, for whatever reason, it happens more regularly.

One of her alternatives is a smoker, even though she is not. Upon waking, she says there are messages in her head that she is a smoker. She describes her lifestyle as “isolated”.

“People consider DID as tragedy” she says, “I just want to make an effort to tell others that we deserve respect, that we are legally accepted members of society, and we hope to live a normal life. I m not stupid, I’m not spiting or running around people with knives. I have a mental problem but try to live a normal life. I completed a course at Harvard, I wrote a book, I m able to communicate well. I mother my two kids well. I’m not on welfare.”

Actually, she volunteers for an organization helping children. She also spends time speaking out about her condition and has written a book on the subject, hoping to help others who are experiencing the same trouble.

Many effects of a lack of sleep, such as being bad-tempered and not working at your best, are well known.【小题1】Regular poor sleep puts you at risk of serious medical conditions,including obesity and heart disease, and it shortens your life expectancy.

How much sleep do we need?

【小题2】But some need more and some less. What matters is that you find out how much sleep you need and then try to achieve it. As a general rule, if you wake up tired and spend the daylonging for a chance to have a nap, it's likely that you're not getting enough sleep.

【小题3】

An occasional night without sleep makes you feel tired and irritable( 急躁易怒 ) the next day,but it won't harm your health. After several sleepless nights, the mental effects become more serious. Your brain will- fog, making it difficult to concentrate and make decisions. 【小题4】

How to catch up on lost sleep?

If you don't get enough sleep, there's only one way to compensate (补偿) —getting more sleep.

【小题5】If you've had months of limited sleep, you'll have built up a big sleep debt, so expect recovery to take several weeks.

Starting on a weekend, try to add on an extra hour or two of sleep a night. The way to do this is to go to bed when you’re tired and allow your body to wake you in the morning (no alarm clocks allowed!).

A bite from a tsetse fly (采采蝇) is an extremely unpleasant experience. It is not like a mosquito, which can put its thin mouthpart directly into your blood, often without you noticing. In contrast, the tsetse fly’s mouth has tiny saws on it that saw into your skin on its way to suck out your blood.

To make matters worse, several species of tsetse fly can transmit diseases. One of the most dangerous is a parasite that causes “sleeping sickness”, or “human African trypanosomiasis” to give it its official name. Without treatment, an infection is usually fatal.

Like so many tropical diseases, sleeping sickness has often been neglected by medical researchers. However, researchers have long endeavored to understand how it avoids our bodies’ defence mechanisms. Some of their insights could now help us eliminate sleeping sickness altogether.

There are two closely-related single-celled parasites that cause this deathly sleep: Trypanosoma brucei rhodesiense and T. b. gambiense. The latter is far more common: it is responsible for up to 95% of cases, mostly in western Africa. It takes several years to kill a person, while T. brucei rhodesiense can cause death within months. There are still other forms that infect livestock.

After the initial bite, sleeping sickness symptoms often start with a fever, headaches and aching muscles. As the illness goes on, those infected become increasingly tired, which is where it gets its name. Personality changes, severe confusion and poor coordination can also happen.

While medication does help, some treatments are toxic and can themselves be deadly, especially if they are given after the disease has reached the brain.

It is worth noting that sleeping sickness is no longer as deadly as it once was. In the early 20th Century several hundred thousand people were infected each year. By the 1960s the disease was considered “under control” and had reached very low numbers, making its spread more difficult. But in the 1970s there was another major epidemic, which took 20 years to control.

Since then, better screening programmes and earlier interventions have reduced the number of cases dramatically. In 2009 there were fewer than 10,000 cases for the first time since records began, and in 2015 this figure dropped to fewer than 3,000, according to the latest figures from the World Health Organisation. The WHO hopes the disease will be completely eliminated by 2020.

While this decline looks positive, there may be many more cases that go unreported in rural Africa. To eliminate the disease completely, infections have to be closely monitored.

More problematically, a series of new studies have shown that the parasite is more complicated than previously believed.

Sleeping sickness has always been considered — and diagnosed — as a blood disease, because T. brucei parasites can readily be detected in the blood of its victims.