Suggestion and Sleep

[Torben Raibeart]

In another thread dealing with how to ensure a frenzied berserker does not end up killing his team-mates, DMofDarkness suggested that one could plant a Suggestion that the berserker falls asleep if attacking an ally.

First of all: Can you Suggestion someone to fall asleep? Is "fall asleep" something a creature is actually capable of doing on command, or does this lead to some sort of error that breaks the Suggestion? Can't see anything in the spell description that says anything about what happens if an impossible course of action is asked for, like "Jump to the moon", but still...

That said, IF you can use Suggestion to make someone fall asleep, what is then the point of ever having the spell Deep Slumber? Same range, same save. Deep Slumber can affect multiple creatures, but Suggestion does not have any HD-cap and can last for HOURS as "The suggested course of activity can continue for the entire duration.". Not to mention the fact that suggestions have more aplications then "make someone fall asleep". Also, Suggestion isn't a magical sleep effect, it is the creature itself that makes itself fall asleep, so one could argue that Suggestion works on creatures such as dragons or elves.

EDIT: Of cause, Deep Slumer does not have the pesky language-dependent thing, but still.