sleep arrow hit dice cap

[Matthew Morris]

Does a sleep arrow have a hit dice cap? Came up in combat today, and the decription on the prd doesn't list hit dice or duration, but based on the DC, it seems like sleep.

[kinevon]

It uses Sleep to create the item, but it doesn't appear to have a cap.

Note that, with that DC, it isn't going to do much against higher hit dice opponents very often.

[Snowblind]

It doesn't mimic the sleep spell explicitly, so it doesn't have a HD cap.

Weirdly enough, it also doesn't have a duration. AFAIK by RAW if nobody woke them up they would sleep till they started taking non-lethal damage from starvation.