The first step in improving your memory is gaining an understanding of how the mind works. It isn't like a tape recorder that perfectly preserves every name, number, or appointment. Instead, memory is like a sound studio's mixing board, combining elements so they relate and harmonize—and eliminating what's not needed. "Your mind is designed to forget," says Dr. Gordon. "Imagine if you remembered every place you ever parked your car. Your brain would be so cluttered that you'd have trouble conjuring things that were more important." This might explain studies that show that you may lose more than half of what enters your head within an hour and 80% within a month.
New information first goes into "working memory," where it's held for a short time while you sort your thoughts. "It's like a scratch pad for your brain," says Cynthia Green, Ph.D., author of Total Memory Workout: 8 Easy Steps to Maximum Memory Fitness (Bantam). "Some of what you note, you'll save, but you'll throw a lot of it away." Information that's reinforced—possibly because it's important to you or linked to an emotion—moves into long-term memory, where it could stick for the rest of your life.
Of course, shuffling memories to long-term storage is more difficult if you are sleep-deprived, distracted, or continually flooded with new material. Hormonal changes can also wreak some havoc: Studies have linked low estrogen levels (say, during your period or when you're in perimenopause) to forgetfulness and fuzzy thinking. Plus, starting in your 20s, brain activity begins to slow, making you less able to focus on new information or process it quickly. "Slowing isn't the same thing as having less ability," says Dr. Gordon. "Most people maintain accuracy and the ability to learn for a long time."
He adds that some forms of memory actually get better with age. Memory loss is usually limited to an area of the brain that handles material tied to specific dates or times—like your parents' anniversary or the last time you changed your water filter. But "skill memory," or your ability to do familiar tasks, and "intelligent memory," which relates to judgment and social skills, improves over time.