I did it. I went to bed angry. They tell you not to, but I did. And I lived to tell the tale.

We were in bed, having one of those “Why can’t you just say the right thing?”/”Why can’t you just tell me what to say?” arguments, when my eyes began stinging from lack of sleep. So I shut them. Just for a second, just to rest. But I maintained a fabulously formidable scowl to show my opponent that our spat was still very much in play.

I woke up seven hours later — scowling — and even more outraged than I’d been the night before. The row was unresolved and now we had broken the cardinal rule of couplehood, too; no good could come of this …

It was only weeks ago, while lunching at Stella Mare’s, that we got to chatting with an elderly couple sitting near us. Holding hands and beaming like the stars of a Cialis commercial, they told us their “secret”: “Never go to bed angry.”

Seriously? I thought. That’s it? That lame old saw? I’d never really understood the adage because I never go to bed angry. I can’t. To me, going to bed mad means I’ve lost the argument. Which is something I don’t do willingly.

“I have a tough time sleeping until I have my say!” echoes a friend who has woken her husband at 2 a.m. just to make a painstakingly worded point.

Some friends agree that disputes should end when the day does. “There’s nothing worse,” says a young woman I know, “than waking up the next morning only to realize, ‘Great, we still have that to deal with.'”

But should such disagreements be debated on your pillow-top Posturepedic? “Go to bed mad, but don’t go to sleep mad,” advises one husband. “Work out the kinks while you’re warm and cozy. Beds don’t have doors to slam — and turning over and looking away is not nearly as frustrating as walking away.”

Others say bed is the first place they head when they’re pissed at their partners. “I’m too tired to deal with it at night, which isn’t conducive to a rational discussion,” says one gal.

If you’re lucky, sleep can do more than mitigate a fight; it can prevent it outright. “I’ve gone to bed angry and woken up happy that I didn’t express it the night before,” admits another friend. “Morning light seems to shrink the issues.”

So, is the best marital advice really, “Pay no attention to what old people tell you about relationships”? Is the old “sleep secret” just so much hooey?

“I give it a fair amount of truth,” says S.B. therapist Gary Linker, PhD. “I don’t think that prolonged anger helps a relationship. That doesn’t mean that if we’re angry, we need to decide at 11 or 12 o’clock at night that we need to thoroughly resolve this issue right now.”

He suggests that couples listen to — and in fact hear — each other’s viewpoints, then agree to revisit the issue tomorrow. “When there’s at least a plan in place, then that anger dissipates and the goodwill, the foundational base of the relationship, is reestablished.”

Or you can endure the kind of odious morning-after that I did: stomping around the house muttering infantile slurs and finally confronting the culprit, who — I swear to you — had no memory of the tiff whatsoever. Which taught me that couplehood is too capricious to rely on trite rules of thumb. You’ve got to be flexible and open-minded.

So the next time I’m livid at lights-out, I’m going to try this new tack from a sensible gal I know: “I say go to bed mad. And plan your revenge.”