The most recent statistics on the women who participate in our Illinois Women’s Health Registry, indicate that sleep is a significant issue in their lives.  Among the most current women who are enrolled in our registry, 11% report difficulties getting to sleep, 12% have a hard time staying asleep, 15% wake up feeling fatigued, 13% report they are getting too little sleep for what they need, and 8% wake too early and cannot get back to sleep.

Our limited knowledge in sex differences is due to the fact that women are underrepresented in studies of sleep and its disorders.  The National Sleep Disorders Research Plan, released in 2004 by the National Center on Sleep Disorders Research reported that 75% of sleep research has been conducted in men.   While more recent sleep studies have included women, the small sample sizes limit sex comparisons.  However, there is a growing body of evidence that sex hormones influence sleep and circadian rhythms, and further neuroendocrine studies are needed.

To read more on women and sleep on the Institute for Women's Health Research, click here.

Many people assume that brain differences between men and women result from sex hormones like estrogen and testosterone. This is not true. In fact, increasing numbers of studies find large reliable distinctions between the sexes. These effects are often seen early in development and before sex hormones are expressed. The research examining sex-specific brain mechanisms finds variability in structure, neurotransmitters, and the expression of specific genes in males and females.

Sex differences in size, shape, and function occur in every region of the brain. For example, sex divergence is seen in the hippocampus, an area of the brain that is important for learning and memory. The hippocampus makes up a larger portion of total brain size in women than in men. But that doesn’t necessarily mean that women learn better than men. Interestingly, some sub-regions of the hippocampus are larger and contain more cells in men. Further studies will be needed to fully understand the implications of such sex differences.

Additional variation occurs in the levels of neurotransmitters, the chemical messengers, in the brain. Males and females differentially produce serotonin, a neurotransmitter that affects mood. These differences may have significant effects on gender-specific treatment of diseases, such as depression.

Gene expression differences between the sexes are also seen across many species. Scientists have found groups of genes with sex-specific expression that are conserved, or maintained, across primate species, suggesting that such patterns are inherited across evolution.

What is the evolutionary advantage to having sex differences in the brain? While we can only guess, one hypothesis is that such variability is important in the selection animals make in finding mates and raising offspring. Whatever the cause, differences in the brain affect development and health during adulthood. Many of the genes with differential expression are also associated with neurological diseases such as Alzheimer’s disease, schizophrenia, and cerebral ischemia. As such, sex-specific treatments of these diseases should also be studied.

__________________________

Kate is also a frequent contributor to the Oncofertility Consortium Blog. Check it out!

You may have seen the cover article on our Spring Newsletter titled “Spotlight on Obesity: Is it just your weight?”  This article focuses not only on the epidemic of obesity in the U.S. but also on the serious health conditions that may result from obesity.  Although obesity is on the rise, however, eating disorders such as anorexia and bulimia still continue to be a problem, especially in women.  According to the National Alliance for the Mentally Ill (2003) 90 percent of individuals with eating disorders are women between the ages of 12 and 25.  Eating disorders are closely correlated with depression, substance abuse, and anxiety disorders, so it is important to diagnose and treat early.

The most common disorders are anorexia nervosa, bulimia nervosa, and binge-eating.  You may already be familiar with these disorders, but they are listed below along with some the complications that may arise.

Anorexia nervosa is a disorder categorized by obsession with weight and food causing individuals to starve themselves or to exercise excessively in order to maintain a weight typically far below the normal weight range for their height and age.  Complications of anorexia include, heart problems, anemia, permanent bone loss, malnourishment, absent menstruation and death.

Bulimia nervosa is categorized by periods of binge eating followed by vomiting or excessive exercise to get rid of extra calories or weight.  Individuals with bulimia are similarly obsessed with weight and food.  Both disorders are closely tied to self-image and thus may be difficult to treat.  Complications of bulimia include heart problems, digestive problems, tooth decay, absent menstruation and death.

Binge-eating disorder is still not considered a psychiatric condition, but may be treated similarly to bulimia and anorexia.  Binge-eaters tend to consume unusually large amounts of food on a consistent basis.  This disorder may lead to obesity and complications associate with obesity such as high blood pressure, diabetes, and heart disease.  In addition binge-eating disorder can cause psychological problems such as depression and suicidal thoughts.

Although the term eating disorder usually means one of the three disorders listed above, the term disordered eating is used to describe a variety of eating abnormalities that do not necessarily fall into, or are not severe enough to be categorized as one of the typical eating disorders.  Disordered eating may not be as serious in terms of complications, but it may lead to more serious eating disorders if left untreated or unaddressed.  According to a survey conducted by Self Magazine and the University of North Carolina, as many as 65% of American women between 25 and 45 exhibit disordered eating behaviors.  Women should not be afraid to seek help for issues they may have with eating, even if they do not think it is a severe eating disorder.  As peers, we should be supportive of women who are suffering from these diseases, and help them to overcome their issues.

We probably all have first hand knowledge of how a bad night's sleep can affect us the next day: we're irritable, in a bad mood, and it can be hard to concentrate. It may not be all that surprising then, that how we sleep can be a very big part of depressive disorders, an incredibly interesting topic covered by Dr. Roseanne Armitage in the most recent installment of the IWHR's Women's Health Research Monthly Forum.

Dr. Roseanne Armitage

Dr. Armitage began her talk by discussing how men and women, even those who do not have depression, sleep in very different ways. Possibly because of the different numbers of hormone receptors  or the over 650 genes that are expressed differently in the brains of males and females, the types of sleep we have also differs. For example, before puberty, boys have more slow wave sleep (stage 3 and 4 sleep, the deep, restorative kind that makes you feel refreshed in the morning) than girls do. After puberty, this changes, and girls are the lucky receivers of more slow wave sleep. Most interestingly, while men have a very slow loss of the amount of slow wave sleep over their lifetimes, women's amount stays relatively level and then drops precipitously during the peri-menopausal years. This is one reason why menopausal women really notice the sudden change in their sleep patterns. In general, women are also more likely to suffer from insomnia and sleep fragmentation than men.

The depression that Dr. Armitage really focused on was untreated MDD (major depressive disorder). MDD is twice as likely to occur in women than in men. Social withdrawal and feelings of worthlessness and guilt are more common in females with depression than in males with depression, who tend to complain more of lack of goal-oriented behavior. Around 80% of people with MDD report sleep problems, and for many people, sleep disturbance is the first presenting symptom of MDD. In adults with MDD, there are increased arousals and episodes of wakefulness, increased stage 1 sleep (the very light sleep), decreased total sleep time, and decreased stage 3 and 4 sleep.

Image:www.sheknows.com

Depression further exacerbates the sex differences in sleep between men and women when faced with a serious change to their normal sleep patterns (such as being asked to stay up for 40 hours consecutively), women with MDD overresponded, staying in slow wave sleep for too long, while men with MDD underresponded.  Sleep in healthy adults also shows a high level of coherence, or a very close association in the activity patterns of the right and left hemispheres of the brain. Women with MDD, however, have a lower coherence during their sleep than other healthy females, healthy males, AND males with MDD.

Dr. Armitage's work also demonstrates the ability to tie sleep disturbances to the likelihood of depression in very young girls. She finds that coherence scores can be a very good predictor of future depressive disorder; girls who were at high-risk for depression because their mothers were depressed demontrate lower coherence in their sleep...even before they have any sign or symptom of depression. Young girls in this high-risk group also had very disorganized sleep-activity patterns, even as disorganized as same aged girls who already suffered from depression. Shockingly, even babies (2 to 30 weeks) of depressed mothers take longer to fall asleep, have decreased total sleep time and sleep efficiency, and spend less time in bright light (known to produce necessary vitamins) than babies of non-depressed mothers.

Our thanks to Dr. Roseanne Armitage for such an eye-opening talk! We encourage you to look at some of Dr. Armitage's published work on the topic:

• "Early developmental changes in sleep in infants: impact of maternal depression"
• "Sex and age differences in sleep macroarchitecture in childhood and adolescent depression"
• "Temporal coherence in ultradian sleep EEG rhythms in a never-depressed, high-risk cohort of female adolescents"