Life desperately needs some form of CC but I'm not sure that this card fills that niche, I wouldn't want to use it on my own criters and I'm not sure if I would want to use it against an opponent either ...
Its certainly has more of a double edged feel than freeze, but then that works thematically I think. I actually would use this offensively to block enemy creatures that have powerful attacks or abilities.
For instance, if the enemy has a mind flayer out, you could use this to gain a few rounds for an important skill (mitosis and rustler spring to mind)
It would also work well if they had an Otyugh or a parasite.
Even though it won't kill the enemy, it will give you several rounds to act. In the case of a mitosis based deck, that could easily turn the tide (sure, the otyugh eats your mitsosis creature in 4 rounds, but by then it has spawned 4 copies). For a nifty example, consider a battle between a pharaoh deck and an otyugh deck. The pharaoh is screwed if the otyugh is already in play. With this spell, they just stun the otyugh to buy some time to get enough scarabs out to survive.
As a defensive heal on my own creatures, its a little more tricky to make it work right.
I see some possible potential with SoP decks here though. It would make the creatures tough to take down while they grow in strength. Another area for use could be the "accelerate" and "overdrive" spells. It would give the creatures several rounds to grow...
More than likely though, this card will be relegated to use on opponents except for a few rare cases.
Speaking of overdrive... Would this "sleep" still allow creatures with, for example the "light" skill, to produce quanta (like delay) or would it prevent that (like freeze and congeal). Would overdive creatures still feel the effects or would they be suspended? What about poison?