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.
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: