The real reason is probably that we don't have enough sleep.

真正的原因可能是我们没有足够的睡眠。

youdao

The study's finding strongly suggests that the real reason why scientists over forty rarely produce highly creative work is not due to age but rather because most have spent too long in their fields.

这项研究的发现有力地表明，40岁以上的科学家很少能做出高度创造性的工作的真正原因不是年龄，而是因为大多数人在他们的领域花了太长时间。

youdao

This was the real reason for her call.

这是她打电话的真实原因。

《柯林斯英汉双解大词典》

And,he said the real reason officials removed the video is because of the exhibit's main subject,gay love.

VOA: special.2010.12.15

There's a reason we like sugar, and there's a real reason when we like the two of them together in something like ice cream.

我们喜欢糖也是有原因的,我们喜欢二者兼备的食物,比如像是冰淇淋,是非常有道理的

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

The real reason of course is laziness.

当然，懒惰才是真正的原因“

耶鲁公开课 - 1945年后的美国小说课程节选

The real reason, especially if true, would be a lot easier to live with.

NPR: Congress, White House Clash on Hearing Rules

You do not like to change things unless there is a real reason for changing.

FORBES: Why Most Businesses Will Keep Buying Microsoft

If the whole thing was a put-on, on some level, what was the real reason?

FORBES: Ten Years Later, It's Still Not Clear Why We Invaded Iraq