Katherine Lewis, a mom of three from Bethesda, MD, didn't know whether to sympathize or scream when her 3-year-old, Ava, would come home from preschool super grumpy and inevitably erupt into tears. "She couldn't even hold it together to speak," Lewis says.

No wonder, says Eileen Kennedy-Moore, Ph.D., an author and child psychologist with a private practice in Princeton, NJ: Preschool is as tiring to its students as work is to adults. "Then there's the tension of having to remember to sit 'crisscross-applesauce,' to follow directions, and to refrain from poking a neighbor in line," adds Kennedy-Moore. To get back on an even keel, try:

Offering pretzels
"Exercising self-control depletes glucose and makes subsequent self-control more difficult," Kennedy-Moore says. A quick snack right after school can help.

Keeping quiet
It's tempting to go run errands right after pick-up; you're already in the car, right? But if you can, put it off until after you both enjoy a little together time, maybe listening to music or chatting about the day.

Making it a habit
Whether it's catching some midday zzz's or vegging out in a rocking chair, your kid will feel soothed if she knows what to expect.