Difference between verb ~ている + (瞬間・とき)


I know that verb + ~ている+ 瞬間【しゅんかん】 has a similar usage to ~ている+とき, for example
目を閉じている瞬間 and 目を閉じているとき.

I want to know what is the difference between these two in general, will it
change the meaning of the sentence if I use しゅんかん over とき？




Japanese 瞬間 always refers to a _very_ short period of time, typically less
than a second. (It can refer to a longer period of time, for example if you're
talking about the history of the earth, though.)

  * 目を閉じる瞬間 the very moment someone closes their eyes
  * 目を閉じている時 when someone's eyes are closed

So you cannot use 瞬間 in the following sentence:

>
> 眠るために目を閉じている時、眼球は素早く運動することがあり、これを[レム睡眠](http://en.wikipedia.org/wiki/Rapid_eye_movement_sleep)と呼ぶ。

目を閉じ **ている** 瞬間 is an expression we would seldom encounter. In general, the
progressive form `～ている` implies the situation persists over a longer period of
time, and thus it doesn't go very well with 瞬間.

Only when you know the eyes will be closed for a very short period of time,
you can say something like this:

> [まばたき](http://en.wikipedia.org/wiki/Blink)のために目を閉じている瞬間を、ふだん人間は認識していない。

(I'm sorry, but your "side question" is totally irrelevant to the main
question. Could you ask it separately?)




Japanese 瞬間 always refers to a _very_ short period of time, typically less
than a second. (It can refer to a longer period of time, for example if you're
talking about the history of the earth, though.)

  * 目を閉じる瞬間 the very moment someone closes their eyes
  * 目を閉じている時 when someone's eyes are closed

So you cannot use 瞬間 in the following sentence:

>
> 眠るために目を閉じている時、眼球は素早く運動することがあり、これを[レム睡眠](http://en.wikipedia.org/wiki/Rapid_eye_movement_sleep)と呼ぶ。

目を閉じ **ている** 瞬間 is an expression we would seldom encounter. In general, the
progressive form `～ている` implies the situation persists over a longer period of
time, and thus it doesn't go very well with 瞬間.

Only when you know the eyes will be closed for a very short period of time,
you can say something like this:

> [まばたき](http://en.wikipedia.org/wiki/Blink)のために目を閉じている瞬間を、ふだん人間は認識していない。

(I'm sorry, but your "side question" is totally irrelevant to the main
question. Could you ask it separately?)

