I find its only the first 1/2 nights without that are hard.
After a short amount of days I am more and more comfortable about not having any weed, unlike tobacco, it gets easier the longer you go without (in my, and several friends experiences have shown.

It isnt the time without weed that makes it so bad, its the THOUGHT of having no weed that upsets me more, but once I'm in the situation of not smokin, its fine really.

Try an alternative for a few nights, alchohol or whatever, as much as i dnt enjoy it, its better than bein stone cold ('scuse the pun) sober