Jared Durtschi, an assistant professor in Kansas State University's marriage and family therapy program, says there is no particular age when a child should stop believing in Santa, and that children will often come to realize the truth gradually as they grow older.
"I don't think it's necessary for parents to decide upon a time to tell their children there is no Santa," Durtschi said. "As children develop, the magical thinking that is so common in kids, which allows them to so readily accept all the details of Santa Claus, will give way and they will soon figure it out on their own."
Durtschi said that by telling the truth about Santa before a child has figured it out on his or her own, parents might unintentionally lessen the excitement of the Christmas season for their children.
"Christmas tends to be more fun for those kids who believe in Santa compared to those who do not," he said. "It may be unnecessary to spoil the excitement for the child until they outgrow the belief."
Parents should also be aware that children will often go through a transition period where they still have some belief in Santa or want to believe in him, but their logic is beginning to tell them the idea is impossible.
During this period, which may last several years, Durtschi said that children's ideas about Santa can change often.
"They may believe one day, not believe the next day, and then decide they believe in Santa again next week after watching a Christmas movie," he said. "Just because a child is showing signs of doubt does not mean he or she has completely made the transition to disbelief in Santa."
This transition period often corresponds with the time that parents are wondering if their child still believes in Santa but are hesitant to raise the subject in case they spoil it for their child. Durtschi advises that parents ask their children a neutral, open-ended question -- "What do you think about Santa Claus?" -- rather than something more leading, such as, "Do you still believe in Santa?"
Parents who do not want their children to believe in Santa may find it difficult to teach them not to because the character is one the mainstream culture heavily promotes.
Durtschi suggests that these parents may find it helpful to spend time with like-minded families during the holiday season, as children generally believe what they are taught from the adults around them.
Durtschi also said that whatever children are taught regarding Santa Claus, it is important for parents to teach them that there may be other children whose beliefs or opinions differ from their own.
"I hope all parents will make efforts to teach their children to respect the differences in how the holidays are celebrated," he said.