Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Let me give you an example: Context: Architecturally, the school has a Catholic character. Atop the Main Building's gold dome is a golden statue of the Virgin Mary. Immediately in front of the Main Building and facing it, is a copper statue of Christ with arms upraised with the legend 'Venite Ad Me Omnes'. Next to the Main Building is the Basilica of the Sacred Heart. Immediately behind the basilica is the Grotto, a Marian place of prayer and reflection. It is a replica of the grotto at Lourdes, France where the Virgin Mary reputedly appeared to Saint Bernadette Soubirous in 1858. At the end of the main drive (and in a direct line that connects through 3 statues and the Gold Dome), is a simple, modern stone statue of Mary.
Question: To whom did the Virgin Mary allegedly appear in 1858 in Lourdes France?
The answer to this example can be: Saint Bernadette Soubirous
Here is why: This is the correct answer. Because the question is asking for the name of the person and following sentence from the passage answers it: It is a replica of the grotto at Lourdes, France where the Virgin Mary reputedly appeared to Saint Bernadette Soubirous in 1858.

OK. solve this:
Context: Restless Legs Syndrome (RLS) or Willis-Ekbom Disease (WED) is highly prevalent, but patients and healthcare providers alike know little about it. Furthermore, controversy persists as to the best way of diagnosing this nosological entity. To verify whether the term used to refer to this disease entity (Restless Legs Syndrome or Willis-Ekbom Disease) affects the prevalence of self-diagnosed RLS/WED in a sample of newly graduated physicians. Newly graduated physicians were asked to self-evaluate for the presence of RLS/WED. Briefly, participants were allocated randomly across two groups. One was asked to self-assess for RLS, while the other was asked to self-assess for WED. The evaluation form given to one group asked 'Do you have Restless Legs Syndrome?' whereas the form given to participants in the other group asked 'Do you have Willis-Ekbom Disease?'. Both forms also contained the four criteria for diagnosing RLS proposed by the International Restless Legs Syndrome Study Group (IRLSSG) and instructions for self-diagnosis according to these criteria. The study sample comprised 1413 newly graduated physicians. Of the 708 participants who were given the form that used the term RLS, 87 (12.28%) diagnosed themselves with the condition. Conversely, of 705 physicians given the form with the term WED, 13 (1.84%) diagnosed themselves with the condition (p<0.0001). A greater proportion of newly graduated physicians diagnosed themselves with RLS/WED when presented with the term Restless Legs Syndrome than when presented with the term Willis-Ekbom Disease. This suggests that the term Restless Legs Syndrome may not be the most appropriate term to denote this nosological entity.
Question: Willis-Ekbom disease is also known as?
Answer:
restless legs syndrome