I am not sure how new a feature this is, but I just today found out we had it. If you type @messages me you will see the list of messages you can set on yourself. The last one, at the time of this writing is @sleep_place. This is used in the exact same way as @look_place, with one small difference, it automatically prepends is sleeping here to all messages. So you write them like this:
@sleep_place me is his face peaceful.
This will result in:
Slither is sleeping here, his face peaceful.
Do not write it like:
@sleep_place me is sleeping here, snoring loudly.
As this will result in:
Slither is sleeping here, is sleeping here, snoring loudly.
Have fun with it, it's a nifty way to let people know where and how you are sleeping!