Meaning of 寝てない


> 昨日｛きのう｝も全然｛ぜんぜん｝ **寝｛ね｝てない** 。*
>
> Yesterday I didn't sleep at all.

Is it 寝る in て-form followed by ある in negative form? Or a contraction of 寝ていない?

Also, why is it not in past form? I thought one should say:

> 寝ていなかった.

*よつばと！Vol. 2 #11 p.7.




寝てない is a very common contraction of 寝ていない, where there is a [subsidiary
verb](https://japanese.stackexchange.com/a/18965/5010) いる. See [this
chart](https://japanese.stackexchange.com/a/18159/5010). To clarify, the
simple nai-form of 寝る is 寝ない, since 寝る is a vowel-stem (aka ichidan) verb.

いる in this case is analogous to English _present perfect aspect_ (eg, "have
slept"), which describes the continuation of some state (in your sentence,
sleeplessness). See the discussion in this question: [When is Vている the
continuation of action and when is it the continuation of
state?](https://japanese.stackexchange.com/q/3122/5010)

You would probably say to someone who just woke up, using the past tense:

> よく寝た? Did you sleep well?

But when you see someone who looks sleepy at work, something like this is more
likely to be heard:

> 昨日あまり寝てないの? Haven't you slept well last night?




寝てない is a very common contraction of 寝ていない, where there is a [subsidiary
verb](https://japanese.stackexchange.com/a/18965/5010) いる. See [this
chart](https://japanese.stackexchange.com/a/18159/5010). To clarify, the
simple nai-form of 寝る is 寝ない, since 寝る is a vowel-stem (aka ichidan) verb.

いる in this case is analogous to English _present perfect aspect_ (eg, "have
slept"), which describes the continuation of some state (in your sentence,
sleeplessness). See the discussion in this question: [When is Vている the
continuation of action and when is it the continuation of
state?](https://japanese.stackexchange.com/q/3122/5010)

You would probably say to someone who just woke up, using the past tense:

> よく寝た? Did you sleep well?

But when you see someone who looks sleepy at work, something like this is more
likely to be heard:

> 昨日あまり寝てないの? Haven't you slept well last night?

