This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

Studies by Nathaniel Kleitman in 1938 and by Derk-Jan Dijk and Charles Czeisler in the 1990s put human subjects on enforced 28-hour sleep–wake cycles, in constant dim light and with other time cues suppressed, for over a month. Because normal people cannot entrain to a 28-hour day in dim light if at all,[citation needed] this is referred to as a forced desynchrony protocol. Sleep and wake episodes are uncoupled from the endogenous circadian period of about 24.18 hours and researchers are allowed to assess the effects of circadian phase on aspects of sleep and wakefulness including sleep latency and other functions.[page needed]
What time cycle did studies in 1938 and 1990s use on humans?

In 1953, the Republican Party's Old Guard presented Eisenhower with a dilemma by insisting he disavow the Yalta Agreements as beyond the constitutional authority of the Executive Branch; however, the death of Joseph Stalin in March 1953 made the matter a practical moot point. At this time Eisenhower gave his Chance for Peace speech in which he attempted, unsuccessfully, to forestall the nuclear arms race with the Soviet Union by suggesting multiple opportunities presented by peaceful uses of nuclear materials. Biographer Stephen Ambrose opined that this was the best speech of Eisenhower's presidency.
What agreements did the GOP Old Guard want Eisenhower to abandon?

Following Thein Sein's first ever visit to the UK and a meeting with Prime Minister David Cameron, the Myanmar president declared that all of his nation's political prisoners will be released by the end of 2013, in addition to a statement of support for the well-being of the Rohingya Muslim community. In a speech at Chatham House, he revealed that "We [Myanmar government] are reviewing all cases. I guarantee to you that by the end of this year, there will be no prisoners of conscience in Myanmar.", in addition to expressing a desire to strengthen links between the UK and Myanmar's military forces.
What official was the first to visit the grounds of Great Britain from Burma?