Remember the mood ring? Those one-size-fits-all rings with stones that purportedly changed colors according to your emotions?

The idea wasn't as far off the mark as you might think.

The ring probably didn't give away anybody's secret desires, or even specific emotions, but it probably did reflect, to some extent, the same sort of physiological arousal measured in biofeedback clinics with elaborate electronic measuring equipment. In other words, a state of stress.

So it was probably inevitable that somebody would invent a biofeedback ring.

People in biofeedback therapies learn that when they are under tension, the tiny blood vessels in their skin contract, thereby lowering the skin temperature. Learning how to raise the skin temperature--by warming the hands from within--can lower blood pressure, abort migraine headaches and help control Raynaud's disease (a syndrome in which the extremities become painfully cold).

Successful biofeedback therapy helps the patient learn how it "feels" during times of stress and relaxation. Muscle-tension and skin-temperature readings help reinforce those feelings enough to teach the patient to practice self-regulation techniques outside of the lab, usually with no special equipment. Some clinics provide mini-thermometers and other devices for use at home.

The new biofeedback ring, called Bio-Q by inventor Robert Kall, is basically a portable thermometer with chemically treated multicolored dots whose change of color can warn that skin temperature is dropping: a possible sign of an oncoming migraine headache or, generally, increasing stress.

The rings, used as adjunct tools in biofeedback clinics for some time, now are available to the public with instructions for learning the technique. A biofeedback/family therapist at the Georgetown Family Center calls the $20 ring "sturdier and better looking" than many of the other optional accessories sprouting up around biofeedback therapy.

Although routine relaxation techniques are good for everyone, any long-term, intensive foray into deep relaxation is accompanied by its own dangers. Deep relaxation can cause hormonal changes--lowered blood sugar, for one--and ought not to be ventured without at least the approval, and preferably the monitoring, of a physician or trained therapist.

For information on the rings: Futurehealth, Inc. 2133 Bristol Pike, Bensalem, Pa. 19020. For information on certified biofeedback therapists: Biofeedback Certification Institute of America, 4301 Owens St. Wheat Ridge, Colo. 80033.

You might call it "Shades Syndrome."

The symptoms are facial numbness below the eyes, side of the nose, upper lip and front teeth, especially while chewing. A med student at the University of Arizona says not to worry. Just switch sunglasses.

According to the Health Insurance News, the student, Grant Gwinup, found that large sunglass frames can press on a nerve in the cheek causing the symptoms, which usually appear after about two weeks of summer shade-wearing and take about that long to go away after you have traded style for sensibility.

More on how ha-ha-ho-ho is good for you comes this month from Parents magazine, where it is declared that a good laugh also is good for the kiddies. And laughing together is best of all.

It doesn't matter, say the experts, whether the humor is clowning, telling jokes or kidding. But it is important that nobody is the butt of the humor and everybody gets to enjoy it. Less sarcasm, in other words, and more silliness.

The trouble, acknowledges one of the experts quoted in the article, is that while specialists know that humor helps, they haven't figured out how to teach "the skills parents can use to lighten communication and make their families closer."

We know a family that's always been X-rated so far as family humor is concerned--"Saturday Night Live" is Shirley Temple compared to them--but they laugh a lot and always have.

In another family, the kiddies are too young to know about Monty Python, but they have regular sessions of "Silly Walks."

In lieu of that, there are always silly songs. Try, for example, singing "George Washington Bridge" over and over to the tune of the "Skater's Waltz." (George Washington Bridge, George Washington, Washington Bridge, George Washington Bridge, George Washington, Washington Bridge ad infinitum.) Ad nauseum too, but silly? Believe it.

And you'll never laugh alone. Neither will they. Nobody does.