menstrual cycle

Women's age at first menstrual cycle linked to heart disease risk

December 15, 2014

Science Daily/American Heart Association

The risk of heart disease, stroke and high blood pressure was significantly higher when menstruation began at age 10 or younger, or age 17 or older. First menstrual cycle at the age of 13 posed the lowest risk of heart disease, stroke and high blood pressure.

 

Researchers analyzed data collected from 1.3 million women aged 50 to 64 years old, who were mostly white. After over a decade of observation, those women who had their first menstrual cycle at the age of 13 had the least risk of developing heart disease, stroke, and high blood pressure.

 

Compared to women who had their first menstrual cycle at age 13, women with their first menstrual cycle at age 10 or younger, or age 17 or older, had up to:

 

  • ·      27 percent more hospitalizations or deaths due to heart disease;
  • ·      16 percent more hospitalizations or deaths from stroke; and
  • ·      20 percent more hospitalizations with high blood pressure, or deaths due to its complications.

 

"The size of our study, the wide range of ages considered, and the vascular diseases being examined made it unique and informative," said Dexter Canoy, M.D, Ph.D., study lead author and cardiovascular epidemiologist at the Cancer Epidemiology Unit, Nuffield Department of Population Health at the University of Oxford in the U.K.

 

"Childhood obesity, widespread in many industrialized countries, is linked particularly to early age at which the first menstrual cycle occurs. Public health strategies to tackle childhood obesity may possibly prevent the lowering of the average age of first menstrual cycle, which may in turn reduce their risk of developing heart disease over the long term."

 

The effect of age of the first occurrence of menstruation on heart disease was consistently found among lean, over-weight, and obese women, among never, past or current smokers, and among women in lower, middle, or higher socioeconomic groups.

 

For the majority of these women, however, their additional risk of developing a vascular disease was small. Of the million women, only four percent of them had their first menstrual cycle occurring at age 10 or younger, and only one percent at age 17 or older.

http://www.sciencedaily.com/releases/2014/12/141215185203.htm

Could quality of sleep have to do with sex differences?

September 12, 2016
Science Daily/McGill University
You may have noticed that women are more prone to sleep disturbances than men. They are, for instance, up to twice as likely to suffer from insomnia than men. Could there be a link between the body clock that regulates sleep and being a female or a male? Yes, according to a new study.

By controlling for the menstrual cycle and hormonal contraceptive use, Dr. Boivin shows, in the Proceedings of the National Academy of Sciences (PNAS), that the body clock affects sleep and alertness differently in men and women.

"For a similar sleep schedule, we find that women's body clock causes them to fall asleep and wake up earlier than men. The reason is simple: their body clock is shifted to a more easterly time zone," says the Director of the Centre for Study and Treatment of Circadian Rhythms at the Douglas Institute, one of the research centres of the CIUSSS de l'Ouest-de-l'Île-de-Montréal.

And, she adds, "This observed difference between the sexes is essential for understanding why women are more prone to disturbed sleep than men."

A novel experiment

In this study, the medical researcher's team compared in 15 men and 11 women variations in sleep and alertness regulated by the body clock. The women who were recruited were cycling naturally and were studied during two phases of their menstrual cycle. This is a crucial point because previous research by Dr. Boivin had shown that the phase of the menstrual cycle affects the biological rhythms of body temperature and sleep.

 

"Our participants did not exhibit any sleep problems during the study. Just the same, our results are helping us understand, among other things, why women are more likely than men to wake up earlier in the morning and feel tired after a night's sleep. As well, women are less alert at night than men," explains Boivin.

 

Thus, the results of this study hint that women could be less biologically suited for night work. Further research will be necessary to explore this matter and develop interventions suited to men's and women's health.

 

More than a third of the Canadian population experiences sleep disturbances. One consequence of this is that close to 15% of adults have functional problems.

https://www.sciencedaily.com/releases/2016/09/160912161058.htm

 

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