By STEVE STEINBERG / The Dallas Morning News

With a big day coming up, do you ever check the alignment of the stars?

That is so last-millennium. Gabrielle Lichterman thinks it makes more sense to check the day of the month.

Ms. Lichterman, a veteran health journalist, has written 28 Days: What Your Cycle Reveals About Your Love Life, Moods, and Potential (Adams Media, $14.95). It's a daily guide for pre-menopausal women to plan their activities based on their hormone levels.

"This is based on research," says Ms. Lichterman, 34, a former editor of the WebMD.com newsletters who lives in New York City and has written about health for popular magazines for 10 years.

Scientists have long known that hormones affect not only mood, but learning, memory and other brain functions.

In 1999, Ms. Lichterman says, she read a study in Nature reporting that on high-estrogen days, women were attracted to masculine-looking men. On low-estrogen days, they were drawn to feminine-looking men.

"I thought there have to be other studies like this that are just as surprising. ... If hormones do this, they must do other things," she says.

So she started reading up on endocrinology, looking for all the hormone studies she could find.

She found plenty. "But none of the books put the effects in dateline order," she says. "It seemed to be the obvious thing to do."

So she structured her breezily written book on a woman's 28-day cycle (Day 1 is the first day of menstruation) and the likely levels of estrogen, progesterone and testosterone. Individual cycles may differ, Ms. Lichterman says, but the book serves as a useful road map.

"Every day has its strength and weaknesses," she says, giving examples. "Days 4-10 are best for asking for a raise or planning a wedding – you have rising estrogen and testosterone, sharpening memory, brain, logic.

"Days 20-22, when progesterone is peaking, are best for doing stuff that makes you nervous. It's a sedating hormone that mellows you."

What about the days it's not so great to do certain things?

"I wouldn't plan interviews on Day 22," she says. "Progesterone peaks then, and it interrupts verbal ability."

Here's the big thing about knowing what your hormones are up to, though:

"If you can't control the schedule, the great thing about knowing what your day is going to be like is that you can play up your strengths and avoid your weaknesses," Ms. Lichterman says.

Let's say you've had to schedule an important speaking engagement on a bad-hormone day. You get a little more rest the night before. You prepare your notes a little more carefully. You speak a little more slowly and clearly. You have a relaxing cup of tea beforehand.

"You're not helpless," Ms. Lichterman says. "The more you know, the more you can control."

At least one local hormone expert says Ms. Lichterman may be on to something.

"There's a certain amount of biological plausibility here," says Dallas reproductive endocrinologist Karen Bradshaw.

"There's pretty good evidence that estrogen, progesterone and testosterone do affect our moods and behaviors," says Dr. Bradshaw, a professor of obstetrics and gynecology at the University of Texas Southwestern Medical School at Dallas.

"But I think we need to take this with a grain of salt," she cautions.

"Remember the old 'PMS defense' for capital murder? You have to stop this at some point."

However, she notes that studies do seem to back up 28 Days' central thesis.

"There's good evidence that estrogen improves mood and memory," she says. For example, she says, lupron is used to treat endometriosis. It smothers estrogen production – and, in the process, mood and memory suffer. "The same thing happens if you take a woman's ovaries out," Dr. Bradshaw says.

She also notes, "Progesterone at certain levels can indeed make people relaxed and peaceful." At high levels, it can even serve as an anesthetic, she says.

Dr. Bradshaw has some doubts about Ms. Lichterman's assertion that 28 Days can work even for women who are on birth-control pills.

"If you're on birth control pills, you're not ovulating," Dr. Bradshaw says. The pill, she explains, keeps the body from making the hormones that drive ovulation.

"So your ovaries are essentially shut down," she says. Instead, you're getting hormones in artificial form – and at fairly constant levels, if you take a monophasic pill. So if those levels don't fluctuate much, neither should mind nor mood.

"In the seven days off the pill each month, some women will have mood changes or headaches. But that's also when they're having their period," Dr. Bradshaw says.

She acknowledges, though, that it might be a little different for women who take the triphasic form of the pill, which changes hormone levels over the course of the monthly cycle.

And in the book, Ms. Lichterman does make a distinction between the different kinds of birth-control pills and their hormonal effects.

Bottom line? "I think her book is fun," says Dr. Bradshaw. "I think it's going to be a best seller. Now, if she could only tell us how to lose weight ..."

While 28 Days is intended for women, it can also open men's eyes, Ms. Lichterman says.

"It really takes the mystery out of women. Women seem to be moody – great moods, then sour moods, then days they can't seem to do anything right. Days when they're so loving, then days when they can't stand to be near you. This explains it all and shows men that they can plan their lives around them."

Men do have their own endocrine patterns, though. In fact, Ms. Lichterman is already planning a 28 Days-style book on guys and their hormones.

So tell us ... does beer count?

A '28 DAYS' SAMPLER

Money: Free-spending testosterone has you whipping out your credit card with the frequency of Joan Rivers at a plastic surgery convention. But you're not totally off the hook with your wild splurging. With your analyzing left brain now in full gear, you're automatically keeping a mental tally of just how much you're buying.

Career: Lucky for you, from today till Day 10, estrogen and testosterone reach levels that give you the best chance of hearing a yes for any of your requests. ... While you're at it, speak more s-l-o-w-l-y and make your voice sound deeper. Estrogen and testosterone are speeding up your speaking pace and raising the pitch of your voice.

Mind: Today you begin the transformation from your superwoman-brain-skills phase to your ordinary woman-without-superpowers phase.

Romance: If your mate plays it smart, today he'll lie low and shower you with compliments and gifts. Many gifts. That's because this is the final day that your hormones are pushing you to check out other lads who might be stronger and healthier genetic matchups for your ovum.

Fat-burning alert! Exercise feels easier to do and burns up to 30 percent more fat today through Day 26! Researchers say it's because the estrogen and progesterone combo during this phase promotes the use of body fat as energy.

Mood: Estrogen withdrawal ... gives rise to bouts of nervousness, anxiety, teariness, and the blues. ... Meanwhile, withdrawing testosterone erodes your self-confidence and has you doubting your talents, skills and especially your appearance.

Sex: In an unexpected twist, your libido shoots up today and keeps increasing all the way through Day 28. Even as sex-craving testosterone continues to take a serious dive? Yes. Even as libido-dampening progesterone is still on the scene? Yes, yes.

Energy: You're tired, sluggish and longing for a nap as estrogen and testosterone continue their downward slide and take your energy and endurance with them. And, adding drowsiness to exhaustion, sleep is less restorative as noradrenaline bursts and increased sensitivity to pain, odors and noise wake you up in the middle of the night.

SOURCE: 28 Days: What Your Cycle Reveals About Your Love Life, Moods, and Potential