The effects of sleep deprivation are a major field of chronobiology research. Sleep deprivation can lower the immune system, increase the risk of developing chronic disease and have a negative effect on neurological and cognitive function. However, a new study suggests that these effects may depend a great deal on the sleep-deprived person’s gender.

What Happens to a Sleep Deprived Brain?

Sleep is when your brain removes toxins, repairs cell damage and induces the production of hormones that prepare the body for a new day. When people are sleep deprived, there is actual shrinkage in certain brain areas, causing sufferers to lose the ability to make new memories, control their emotions, assess risk and more. In addition, the levels of melatonin, cortisol and other hormones become unstable and fail to be produced in the right amounts at the right times.

Men and women have been found in numerous studies to have slight differences in their brains, both in anatomy and in function. Thus, it was not a surprise when a recent study in circadian biology found that the reaction to sleep deprivation is often affected by gender.

Sleep Deprivation and Risk Taking Behavior

A recent NIH study took college students and deprived them of sleep before asking them to perform cognitive tasks, including making decisions. Researchers expected to see differences in decision-making ability and risk-taking behavior, as sleep deprivation has been found to cause a higher rate of accidents and bad decisions. However, they were surprised to find a wide gender disparity. Men were more likely to engage in risky behavior when sleep deprived, while women actually became more risk averse. Both groups showed a marked change in their ability to handle risk, but the changes were in opposite directions.

Women tend to be more risk-averse in general, which is believed to be due to gender differences in which areas of the prefrontal cortex of the brain are activated. The prefrontal cortex is a region in the front of the brain that controls impulses and helps people to make wise decisions. Researchers suspect that sleep deprivation affects these areas differently. However, there were other, more subtle differences noted. Women, for example, became more altruistic when sleep deprived while men did not. This was a small study, with just over 30 participants, so more research will be needed to work out these fine details.

Blood Pressure and Hormones

This is not the only study to examine sex-related differences in reaction to sleep deprivation. Another NIH study looked at why women are more likely to develop hypertension, also known as high blood pressure, as a result of sleep deprivation. While men are more susceptible to hypertension and cardiovascular disease in general, women are more likely to develop high blood pressure as a result of chronic sleep deprivation.

The exact biochemical mechanism has not been determined, but researchers postulate female hormones such as estrogen and progesterone may be the missing link. These hormones become less stable when women are sleep deprived, which may cause a “fight or flight’ reaction in the sympathetic nervous system. The sympathetic nervous system is a part of the nervous system that reacts to stress and danger by preparing the body for intense physical activity. This reaction includes the large-scale release of epinephrine, a stress hormone also known as adrenaline, which raises blood pressure.

With only about 30 percent of American adults getting the amount of sleep they need, it is important to understand what happens to the sleep deprived body and how these effects can be successfully mitigated. However, these new studies in chronobiology also point out new and interesting differences between the male and female body’s reaction to different stressors.