For most new parents, nothing seems so elusive - or so desperately needed - as a good night's sleep. But how to convince a wakeful young baby to cooperate?

The answer, according to a recent study at Washington University in St. Louis, is a sensible system of encouragement. Doctoral research by Dr. Amy R. Wolfson has demonstrated that training new parents in simple behavioral strategies can have a dramatic impact on their baby's sleep patterns and on their own emotional health. These findings are to be presented this month during the annual meeting of the Association for the Advancement of Behavior Therapy in New York City.Wolfson's study, "The Effects of Parent Training on the Development of Infant Sleeping Patterns," emphasized a preventive approach. She trained small groups of first-time parents in four pre- and post-natal sessions. Then she compared the experiences of these parents with those of untrained counterparts, first when their babies were 6 to 9 weeks old, and again at 4 to 5 months.

The strategies she suggested were aimed at persuading babies to become "independent sleepers," says Dr. Patricia E. Lacks, Wolfson's graduate adviser and a sleep specialist. "You want babies to learn to put themselves to sleep and, if they wake up in the night, to get themselves back to sleep."

But the training also had a subtler purpose: to instill more confidence in anxious parents. If they were educated about infant sleep patterns, reasoned Wolfson and Lacks, these parents should feel more in control of their baby's sleep schedule. Parents should wake up less often, for example, and respond less often to the child's whimpering.

The results showed vividly that parents who were trained achieved both goals. At the 6- to 9-week check, infants in the training group had begun sleeping through the night much sooner than those in the untrained group. At 4 to 5 months, their sleep remained better. And their parents reported feeling more competent and less stressed in handling their babies' sleep schedules. Like many new parents, however, both groups also reported decreased marital satisfaction during their transition to parenthood.

"Clearly, preventive parent training has a powerful influence on the maturation of infant sleeping patterns," says Wolfson, who is now a post-doctoral research associate in the psychology department at Stanford University.

To begin the study, Wolfson recruited 60 couples from Lamaze childbirth classes at St. Mary's Health Center in St. Louis. They were a homogeneous group: mostly middle-class, college-educated, working; and all married, 21 to 40 years old, and first-time parents. She randomly assigned 29 to the training group and 31 to the control group.

The trainees met for two prenatal sessions in which they received training and completed questionnaires. Two post-natal sessions followed when the babies, all born between September 1986 and January 1987, were "settling-ready": weighing 9 to 10 pounds, gaining weight, healthy and at least 6 weeks old. At the first follow-up session, parents were given daily "infant sleep diaries" to keep for three weeks; at the second, they received one-week diaries.

In developing the training, Wolfson and Lacks adapted tactics suggested in the book, "Helping Your Child Sleep Through the Night," by Joanne Cuthbertson and Susie Schevill, published in 1985 by Doubleday & Company Inc. These strategies are also outlined in an award-winning videotape, based on the book. The 24-minute tape, designed for viewing by new parents, was produced by the Media Center for Health Concerns in Albany, Calif.

At Wolfson's two prenatal sessions, she focused on infant behavior during the early weeks and on steps parents can take to help prepare their infant son or daughter for sleeping through the night.

-Don't hold, rock or nurse the baby to sleep. Wrap the baby snugly and allow it to fall asleep on its own. Put the baby to sleep in its own bed.

-Teach the baby the difference between day and night. Limit daytime nap periods and play with it often. During naps, don't darken the room; allow normal household noises to continue. Don't stimulate the baby just before bedtime and don't turn on its light at night.

-Establish one late-night "focal feeding" just before your own bedtime, even if you must wake the baby up to provide it. With a full stomach, the baby should sleep longer.

-Wait to pick up the baby until it is really complaining. Don't rush in at the first whimper; the baby may be able to "self-soothe," and get back to sleep on its own.

At her second prenatal session, Wolfson discussed a four-night program that parents can use to convince "settling-ready" babies to sleep through the night. The plan involves providing a later focal feeding; stretching the time between middle-of-the-night feedings; and waiting to go to a fussy baby.

The two post-natal sessions reinforced these techniques and gave parents a chance to discuss problems. While control groups did not receive any training, they completed the same questionnaire and diaries that the trainees did.

This study had its roots in seven years of adult insomnia treatment research done by Patricia Lacks. On the average, her subjects had a 14-year history of insomnia, but many had been fighting the problem for up to 40 years.

That led Lacks and Wolfson to wonder whether encouraging good sleep in young babies might establish sound sleep patterns that would persist throughout their lives. And the parents would benefit immediately from reduced stress in the early months.

In fact, adds Lacks, a sleep routine is healthy not just for children, but for babies too. They derive security from a predictable schedule that includes regular times to wake up, eat meals, and go to bed. When bedtime becomes a negotiable issue each night, it's exhausting for parents and children alike.

Parents unwilling to enforce any sleep schedule are sometimes two-career couples who want their babies to stay awake as long as possible each evening. Or they may be people reacting to their own parents' more authoritarian child-rearing style, Lacks says. Striving to be democratic, they take all their child's opinions into account.