Why is the causative of "neru" "nekaseru".

Following the standard rules, it should be "nesaseru". It isn't listed as a irregular verb either.

What am I missing?

  • 1
    @AlexanderZ I'm afraid you shouldn't answer the question in the comment. japanese.stackexchange.com/help/privileges/comment
    – Spoonail
    Apr 27, 2020 at 15:22
  • 2
    You're missing the fact that nekaseru is a verb in its own right. An interesting question might be what the difference is between nekasu, nekaseru and nesaseru (well I'd be interested anyway. Sleep verbs really confuse me). Apr 27, 2020 at 15:45

1 Answer 1


The verb 寝かせる is not the causative form of 寝る, but it is related. The causative form of 寝る is 寝させる.

寝かせる is instead a transitive verb closer in tone to "put to bed" than literally "make sleep" or "let sleep".

Japanese is much richer in terms of transitive/intransitive groups of verbs with similar sound and meaning. English has a few: lay/lie, raise/rise, "they fell trees"/"trees fall". Japanese has many more groupings like this, in addition to causative markings: the transitive verb 開ける means "(someone) opens (something)", the intransitive 開く means "(something) opens (up)", and the causative 開かせる means "(someone) makes (something) open (up)". Although they are all possible, context will often dictate which one is most appropriate for each group of verbs.

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