Everybody, right?

Everyone knows that women go a little crazy

right before they get their period,

that the menstrual cycle throws them onto an inevitable hormonal roller coaster

of irrationality and irritability.

There's a general assumption

that fluctuations in reproductive hormones cause extreme emotions

and that the great majority of women are affected by this.

Well, I am here to tell you that scientific evidence says

neither of those assumptions is true.

I'm here to give you the good news about PMS.

But first, let's take a look at how firmly the idea of PMS

is entrenched in American culture.

If you examine newspaper or magazine articles,

you'll see how widely assumed it is that everyone gets PMS.

In an article in the magazine Redbook titled "You: PMS Free,"

readers were informed that between 80 to 90 percent of women suffer from PMS.

L.A. Muscle magazine warned its readers

that 40 to 50 percent of women suffer from PMS,

and that it plays a major role in women's mental and physical health,

and a couple of years ago, even the Wall Street Journal

ran an article on calcium as a treatment for PMS,

asking its female readers,

"Do you turn into a witch every month?"

From all these articles, you would think there must be a mountain of research

verifying the widespread nature of PMS.

However, after five decades of research,

there's no strong consensus on the definition, the cause,

the treatment, or even the existence of PMS.

As most commonly defined by psychologists,

PMS involves negative behavioral, cognitive and physical symptoms

from the time of ovulation to menstruation.

But here's where it gets tricky.

Over 150 different symptoms have been used to diagnose PMS,

and here are just a few of those.

Now, I want to be clear here.

I'm not saying women don't get some of these symptoms.

What I'm saying is that getting some of these symptoms

doesn't amount to a mental disorder,

and when psychologists come up with a disorder

that's so vaguely defined,

the label eventually becomes meaningless.

With a list of symptoms this long and wide,

I could have PMS, you could have PMS,

the guy in the third row here could have PMS,

my dog could have PMS. (Laughter)

Some researchers said you had to have five symptoms.

Some said three.

Other researchers said that symptoms were only meaningful

if they were highly disturbing to you,

but others said minor symptoms were just as important.

For many years, because there was no standardization

in the definition of PMS,

when psychologists tried to report prevalence rates,

their estimates ranged from five percent of women

to 97 percent of women,

so at the same time almost no one and almost everyone had PMS.

Overall, the weaknesses in the methods of research on PMS have been considerable.

First, many studies asked women to report their symptoms retrospectively,

looking to the past and relying on memory,

which is known to inflate reporting of PMS

compared to what's called prospective reporting,

which involves keeping a daily log of symptoms

for at least two months in a row.

Many studies also exclusively focused on white, middle-class women,

which makes it problematic to apply study findings to all women.

We know there's a strong cultural component to the belief in PMS

because it's nearly unheard of outside of Western nations.

Third, many studies failed to use control groups.

If we want to understand the specific characteristics

of women who have PMS,

we need to be able to compare them to women who don't have PMS.

And finally, many different types of questionnaires were used

to diagnose PMS, focusing on different symptoms,

symptom duration and severity.

To do reliable research on any condition,

scientists must agree on the specific characteristics

that make up that condition

so they're all talking about the same thing,

and with PMS, this has not been the case.

However, in 1994,

the Diagnostic and Statistical Manual of Mental Disorders,

known as the DSM, thankfully --

it's also the manual for mental health professionals --

they redefined PMS as PMDD,

Premenstrual Dysphoric Disorder.

And dysphoria refers to a feeling of agitation or unease.

And according to these new DSM guidelines,

in most menstrual cycles in the last year,

at least five of 11 possible symptoms

must appear in the week before menstruation starts;

the symptoms must improve once menstruation has begun;

and the symptoms must be absent the week after menstruation has ended.

One of these symptoms must come from this list of four:

marked mood swings, irritability, anxiety, or depression.

The other symptoms could come from the first slide

or from those on the second slide,

including symptoms like feeling out of control

and changes in sleep or appetite.

The DSM also required now that the symptoms

should be associated with clinically significant distress --

there should be some kind of disturbance in work

or school or social relationships --

and that symptoms and symptom severity should now be documented

by keeping a daily log for at least two cycles in a row.

And finally, the DSM required that the emotional disturbance

should be more than simply an exacerbation of an already existing disorder.

So scientifically speaking, this is an improvement.

We now have a limited number of symptoms,

and a high impact on functioning that's required,

and the reporting and timing of symptoms have both become very specific.

Well, using this criteria

and looking at most recent studies,

we see that on average,

three to eight percent of women suffer from PMDD.

Not all women, not most women,

not the majority of women, not even a lot of women:

three to eight percent.

For everyone else, variables like stressful events or happy occasions

or even day of the week

are more powerful predictors of mood than time of the month,

and this is the information the scientific community has had

since the 1990s.

In 2002, my colleagues and I published an article

describing the PMS and PMDD research,

and several similar articles have appeared in psychology journals.

The questions is, why hasn't this information trickled down to the public?

Why do these myths persist?

Well, certainly the onslaught of messages that women receive

from books, TV, movies, the Internet, that everyone gets PMS

go a long way in convincing them it must be true.

Research tells us that the more a woman believes that everyone gets PMS,

the more likely she is to erroneously report that she has it.

Let me tell you what I mean by "erroneously."

You might ask her, "Do you have PMS?"

and she says yes,

but then, when you have her keep a daily log

of psychological symptoms for two months,

no correlation is found between her symptoms

and time of the month.

Another reason for the persistence of the PMS myth

has to do with the narrow boundaries of the feminine role.

Feminist psychologists like Joan Chrisler

have suggested that taking on the label of PMS

allows women to express emotions that would otherwise be considered unladylike.

The near universal definition of a good woman

is one who is happy, loving, caring for others,

and taking great satisfaction from that role.

Well, PMS has become a permission slip to be angry, complain, be irritated,

without losing the title of good woman.

We know that the variables in a woman's environment

are much more likely to cause her to be angry than her hormones,

but when she attributes anger to hormones,

she's absolved of responsibility or criticism.

"Oh, that's not who she is. It's out of her control."

And while this can be a useful tool, it serves to invalidate women's emotions.

When people respond to a woman's anger

with the thought, "Oh, it's just that time of the month,"

her ability to be taken seriously or effect change is severely limited.

So who else benefits from the myth of PMS?

Well, I can tell you that treating PMS

has become a profitable, thriving industry.

Amazon.com currently offers over 1,900 books on PMS treatment.

A quick Google search will bring up a cornucopia

of clinics, workshops and seminars.

Reputable Internet sources of medical information

like WebMD or the Mayo Clinic list PMS as a known disorder.

It's not a known disorder, but they list it.

And they also list the medications that physicians have prescribed to treat it,

like anti-depressants or hormones.

Interestingly, though, both websites say that the success of medication

in treating PMS symptoms vary from woman to woman.

Well, that doesn't make sense.

If you've got a distinct disorder with a distinct cause,

which PMS is supposed to be,

then the treatment should bring improvement for a great number of women.

This has not been the case with these treatments,

and FDA regulations say that for a drug to be deemed effective,

a large portion of the target population

should see clinically significant improvement.

So we have not had that at all with these so-called treatments.

However, the financial gain of perpetuating the myth

that PMS is a common mental disorder

and is treatable is quite substantial.

When women are prescribed drugs like anti-depressants or hormones,

medical protocol requires that they have physician follow-up every three months.

That's a lot of doctor visits.

Pharmaceutical companies reap untold profits

when women are convinced they should take a prescribed medication

for all of their child-bearing lives.

Over-the-counter drugs like Midol

even claim to treat PMS symptoms like tension and irritability,

even though they only contain a diuretic, a pain reliever

and caffeine.

Now, far be it from me to argue with the magical powers of caffeine,

but I don't think reducing tension is one of them.

Since 2002, Midol has marketed a Teen Midol to adolescents.

They are aiming at young girls early,

to convince them that everyone gets PMS and that it will make you a monster,

but wait, there's something you can do about it:

Take Midol and you will be a human being again.

In 2013, Midol took in 48 million dollars in sales revenue.

So while perpetuating the myth of PMS has been lucrative for some,

it comes with some serious adverse consequences for women.

First, it contributes to the medicalization

of women's reproductive health.

The medical field has a long history of conceptualizing

women's reproductive processes as illnesses that require treatment,

and this has come at many costs, including excessive Cesarean deliveries,

hysterectomies and prescribed hormone treatments

that have harmed rather than enhanced women's health.

Second, the PMS myth also contributes to the stereotype of women

as irrational and overemotional.

When the menstrual cycle is described as a hormonal roller coaster

that turns women into angry beasts,

it becomes easy to question the competence of all women.

Women have made tremendous strides in the workforce,

but still there's a minuscule number of women at the highest echelons

of fields like government or business,

and when we think about who makes for a good CEO or senator,

someone who has qualities like rationality, steadiness, competence

come to mind,

and in our culture, that sounds more like a man than a woman,

and the PMS myth contributes to that.

Psychologists know that the moods of men and women

are more similar than different.

One study followed men and women for four to six months

and found that the number of mood swings they experienced

and the severity of those mood swings were no different.

And finally, the PMS myth keeps women from dealing

with the actual issues causing them emotional upset.

Individual issues like quality of relationship or work conditions

or societal issues like racism or sexism or the daily grind of poverty

are all strongly related to daily mood.