Medical and psychiatric researchers have been investigating connections between affective illnesses and menstruation in recent years, particularly the overlapping nature of symptoms for PMS and mood disorders as well as the co-morbidity of the illnesses (the number and likelihood of women having both illnesses at once, as well as how the illnesses affect each other). The PMDD criteria of the DSM-IV state that women with recurrent major depressive disorder (MDD), bipolar I or bipolar II or even a family history of such disorders may be at greater risk for PMDD.

Other findings are that women with MDD or rapid-cycling bipolar disorder commonly experience "premenstrual exacerbation" of their mood symptoms; that PMS may trigger affective episodes and that PMS is possibly a unique form of affective disorder; that women with past or current psychiatric illness, principally affective disorders, report a higher incidence of PMS than normal controls; that PMS is not simply always a premenstrual worsening of affective illness but has validity independent of other affective syndromes; that there tends to be a cycle-to-cycle worsening of premenstrual symptoms and depression prior to prolonged episodes of MDD; that women with postpartum depression are more likely to develop premenstrual depressions several months after the resumption of menses; that some women may have a biological vulnerability for mood disorders that is "triggered" by menstrual changes; and that the relationship between PMS and bipolar illness does not always stay static over a woman's lifetime. The cycles do not necessarily coincide, and in some phases the woman may have "pure" PMS/PMDD while at other times she has premenstrual worsening of her mood disorder.

One of the most disturbing similarities between bipolar II and severe PMS is the potentially lethal nature of both illnesses. Goodwin and Jamison's "Manic Depressive Illness" reports that "patients with depressive and manic-depressive illnesses are far more likely to commit suicide than individuals in any other psychiatric or medical risk group." The suicide statistics on PMS sufferers are equally catastrophic. Some studies have shown that up to one-third of severe PMS sufferers have attempted suicide. According to a 1993 study called "The Menstrual Cycle and Mood Disorders" by Dr. Jean Endicott of the New York State Psychiatric Institute, there is evidence that suicide attempts are more likely during the premenstrual phase of the cycle, and "there is evidence from autopsies that completed suicide is more likely to occur during the late luteal phase of the cycle."

Another study, "Premenstrual Tension Syndrome in Rapid-Cycling Bipolar Affective Disorder" by William A. Price and Lynn DiMarzio, notes that "the paramenstruum, the 4 days preceding and the first 4 days of menstruation, is associated with increased rates of medical, surgical, and psychiatric hospitalizations; increased rates of suicide attempts; and increased severity of suicidal intent." These findings support those of Dalton, whose studies of British women have shown that suicide attempts increase 17-fold during the luteal phase as opposed to the preovulatory phase of the cycle.

Though scientific researchers have noted that there is a relationship between bipolar illness and PMS, they have not yet clarified the parameters of that relationship. Nevertheless, it can be cautiously concluded that Plath suffered from some degree of both affective and premenstrual illness, even if how those two illnesses may have corresponded is impossible to detect.

Why does it matter? Why try to understand who Plath was beyond what rises immediately to the surface in her poetry? Perhaps the answer lies first with Plath's ceaseless desire to understand the dendritic and operatic machinations of her psyche, her "million filaments," and how that quest for self became not just the driving force behind her creativity but also the undeniable key to the richly textured artistry it produced.

Plath was ultimately as much an enigma to herself as she is now to us. During the weeks before her death she was fervently engaged in putting together the puzzle of her "Ariel" poems, giving them a logical sequence, a narrative cohesion that amounted to a mythic performative utterance. She was putting them in an order that would tell her the story of her own survival, her phoenixlike eruption from the ashes of her destroyed marriage and the shed skin of her "false" selves.

"Will the hive survive, will the gladiolas/Succeed in banking their fires/To enter another year?" she had asked herself in "Wintering," the poem, almost a prayer, that she chose to end her "Ariel" manuscript in December 1962. "The bees are flying," the poem concludes. "They taste the spring." Plath wanted to know that she would survive that English winter; she willed herself, as she had done countless times before, toward the spring of her inner life.

Understanding Plath's biology underscores her very human, as opposed to iconic, instinct toward self-preservation. If one accepts the possibility that Plath's true demon was not something of her own making but a force, or forces, she was quite powerless against, her attempts to juggle the details of her daily life, to care for herself and her small children alone and furthermore to programmatically write "dawn poems in blood" to save her sanity seem nothing less than courageous.

It also hints at the possibility that Plath's notable premonitory abilities (verging on telepathy), her seemingly numinous sensitivity, may have arisen in some part from a subconscious understanding that her psychological suffering was also the source, in a very material way, of her internal artistic fire -- the fire that would finally burn hot enough to work the alchemical change that Hughes described.

What is breathtaking about the possibility that Plath may have suffered both bipolar II and PMS is that in tandem, those two illnesses totally integrate her daily and imaginative life, her artistic fascinations and her emotional despair, her life as a woman and as a writer, and they do so without diminishing Plath's achievement in any way. Her ars poetica, not just brilliantly executed but brilliantly won despite unbelievable odds, leaps into focus in even more astonishing detail than ever before.

Actress Frances McDormand reads Sylvia Plath's "The Bell Jar"