For more than 20 years, Elizabeth Lloyd Mayer has dedicated herself to her work as a researcher and associate clinical supervisor for the psychology department.

Later this week, Mayer will take a scholarly look at the other passion in her life: the annual celebration of the winter solstice.

In addition to her academic credentials, Mayer is founder and artistic director of San Francisco Bay Revels, a Massachusetts-based theater company that each year produces an elaborate celebration of the time of year when the sun is farthest south of the equator.

"Across the centuries, people have chosen this time to acknowledge and celebrate the cycle of light and darkness," said Mayer.

Decorating homes with lights in mid-winter, for example, is an ancient ritual for "calling back the light" pre-dating Christmas by centuries.

"The message is that even though the night seems never-ending, the light does return, and goodness and life will triumph in the end. This is something we need to hear -- especially at this often depressing, over-commercialized time of year."

Each year, the Revels incorporate drama, music and dance to explore the celebration in different cultures and at different periods. This year's program, scheduled for Dec. 12 to 15 at the Scottish Rite Theater in Oakland, is set in Victorian England.

More than 65,000 are expected to attend Revels in nine cities this season. The San Francisco Bay Revels are Dec. 12 at 7:30 p.m., Dec. 13 and 14 at 8 p.m., and Dec. 15 at 5 p.m. Most matinees are sold out. Adult tickets are $12, $22 and $25. Seniors and children 12 and under, $12. For tickets, call 893-9853 or e-mail sfbayrevels@earthlink.net.