Increasingly, scientific studies are confirming the importance of sleep to our cognitive, physical and emotional states. Now, there’s one more reason to make sure to get a restful 8-hour stretch: lack of sleep has an impact on conception through pregnancy.

Lack of sleep linked to gestational diabetes

A new study published in the journal Sleep Medicine Reviews has found that lack of sleep among pregnant women may be a contributing factor to what causes gestational diabetes.

Gestational diabetes is a condition that most often occurs in the second or third trimester, and affects between 3 to 7% of all pregnancies. Usually, there are no symptoms in the mother, and blood sugar levels return to normal after the baby is born. Babies born to mothers with gestational diabetes tend to have high birth weights. Women who have gestational diabetes are at an increased risk for developing type 2 diabetes later. Their babies are also at an increased risk for type 2 diabetes as well as obesity.

Until this most recent study, by Dr. Sirimon Reutrakul, associate professor of endocrinology, diabetes and metabolism in the University of Illinois at Chicago College of Medicine, some large studies had linked lack of sleep to diabetes, but not in pregnant women. A few studies have linked short sleep duration to elevated blood sugar levels in pregnant women, but many of them were small and their findings not statistically relevant.

Reutrakul and her colleagues performed a meta-analysis of eight studies that included 17,308 pregnant women who were assessed for sleep duration (all studies used self-reported questionnaires except one which measured sleep objectively using an accelerometer) and gestational diabetes. The researchers also obtained raw individual participant data from the authors of four additional studies that included measurements of blood sugar levels and measured sleep duration objectively in 287 pregnant women with gestational diabetes for further analysis.

In their analysis of the studies, the researchers found that average sleep duration of less than 6 hours was associated with a 1.7-fold increase in the risk of being diagnosed with gestational diabetes.

“This is the first meta-analysis to find that both self-reported and objectively measured short sleep duration was associated with elevated blood sugar levels in pregnancy as well as an increased risk for developing gestational diabetes,” Reutrakul said. “More research is needed to confirm our findings, and to determine whether sleep extension may be beneficial in lowering the risk of gestational diabetes.”

Too much or too little sleep may affect sperm DNA

Another study found a link between sleep duration and sperm health. The findings are published in the Journal of Sleep Research.

In the study of 2,020 semen samples provided by 796 male volunteers from colleges in Chongqing, China, volunteers with more than 9 hours of sleep per day and those with 6.5 hours of sleep, or less, per day had the significantly less healthy sperm than volunteers who typically slept 7 to 7.5 hours a day. Sperm health was determined by measuring the proportion of sperm with abnormal chromatin, a complex of DNA and proteins that helps form the chromosomes of a fetus; abnormal chromatin can lead to chromosomal abnormalities in the fetus, which can, among other things, lead to miscarriage.

Interestingly, this study, along with a previous study done by the same team, would seem to support the conclusion that the sperm health parameters decline when there is too little — but also too much — sleep. No doubt, more research would be required to confirm whether it’s the sleep, or other lifestyle factors related to the sleep patterns, that are creating the problem.