How does sleep work?

[Olaf 'Don' Scholz]

Im using the kulu hasta 3 and no matter what, the monsters wont fall asleep! I kill them befor they fall asleep even once, so am I missing something with the sleep effect?

[♋Phenex]

If the element is in brackets which I believe kulu weapons are, the element/status is locked and needs the free elem/ammo up skill in order to unlock the element.

[Nope]

You need to do two thing for them to sleep when they return to their nest
-Do not stay in the same area as them
-Wear Ghillie Mantles

Edit: Now I just realized you talk about status effect
It have pretty high threhold in Iceborne, make sure you have high build up rate on the weapons so they can sleep easier
And like elemental, fast weapons have better build up rate

[Suzaku]

Like other statuses, you build it up with attacks (I think it's every 3rd strike?), and once you've passed the threshold, it activates. Each time it occurs, the threshold increases up to a certain point, making subsequent applications more difficult.

The very first application of any status is usually very easy to activate. I would assume what Phenex said is likely your issue (I'm not at my PC to check your weapon's stats at the moment).

[Flo]

You probably wake them up immediatly as they fall asleep

[Kawalorn]

As said in comment above, Kulu Hasta 3 does not apply sleep until you have Free Element skill in your build. Same for all elements that appear greyed out on the stat screen.

[Smug Kot]

you close you eyes.

[Olaf 'Don' Scholz]

Ah okay thanks for the clarification!