Sleep, if you think about it, is a shared experience for many, as most couples share a bed; one person’s sleep quality often affects the other’s. We kick off this article with a look at how sleep affects romantic relationships, intimacy and sex hormones. 

How does sleep affect sex hormones and the reproductive system?

Sex hormones in both men and women are actually highly dependent on sleep.

Studies have shown that men who sleep for around six hours a day have testosterone levels of men 10 years older(1). Men who sleep for five hours a night also have smaller testicles and those who sleep for six hours or less have fewer sperm(2), with more deformities in the sperm(3).  

For women, FSH and LH are hormones that work together to regulate ovulation and other reproductive processes in the body. One experiment demonstrated that women who get five or six hours of sleep a night face a 20% reduction in FSH, and have a 30% higher rate of abnormal menstrual cycles(4)

As you might have surmised, this spells disaster from a reproductive point of view. We turn next to how romantic relationships are influenced by sleep far more than you might have guessed.

How does sleep affect romantic relationships? 

If your partner or spouse snores or moves around a lot, you might have passed a snarky remark at the breakfast table the next morning. Disturbances in sleep due to a partner’s sleep habits are a lot more common than you think. Sleep apnea(5) or snoring can strip away years from your life if not treated in time, and about 80% of people afflicted with it are undiagnosed. The worst part is, it often means poor sleep or insomnia for both the people sharing the bed.

Sleep expert Matthew Walker suggests(6) you consider a ‘sleep divorce’, wherein you sleep in different beds or rooms, if the lack of sleep is interfering with your life. If you have apprehensions about how the intimacy between the two of you would fare if you sleep separately – don’t worry about it. According to data, since those who sleep in separate rooms will enjoy better quality of sleep, it leads to a better mood – which translates into an improved relationship, as you have more energy and patience for each other. 

Every extra hour of sleep that a woman gets would actually mean a 13 to 15% increase in her desire to be intimate with her partner. So as it turns out, with a ‘sleep divorce’, you might both actually enjoy – both – better sleep as well as better sex. 

We continue looking at sleep and its relationship with matters of the heart – quite literally – in the next section. 

How does sleep affect cardiovascular health? 

If you take a look at the data(7), there is a 24% increase in the risk of a heart attack after daylight saving in spring, whereas there is a 21% decrease in fall. In fact, research shows that there is also an increase in car accidents and suicide attempts during daylight saving. More sunlight might mean more productivity, but the lost hour of sleep certainly has a huge effect on the population in the northern hemisphere.  

The study ‘Short sleep duration and incident coronary artery calcification’ tracked healthy adults without any sign of cardiovascular disease and found, at the end of the study, that those getting less than five hours of sleep had a whopping 200-300% increased risk of coronary artery calcification(8).  

Matthew Walker explains, “If there is one central, common pathway through which we can understand almost all aspects of the deleterious impact of insufficient sleep, it is through the autonomic nervous system, and specifically an excessive leaning on the fight or flight branch of the nervous system.”

The fight or flight branch of the nervous system gets fired up when you’re sleep deprived, which translates into a spike in adrenaline and cortisol – read: more stress! All of these are factors leading to a condition known as atherosclerosis, as a part of which plaque builds up in the arteries in your heart. Sleep deprivation also increases blood pressure or hypertension.

All in all, it looks like sleep deprivation does seem to accelerate or worsen cardiovascular health issues. 

How does sleep deprivation affect the immune system?

Having discussed the importance of the immune system in this piece , we now take a look at how sleep affects the immune system. Physician Peter Attia, in this podcast, discusses why cancer increases non-linearly as you grow older. While there are a few hypotheses which are relevant, most experts agree that the weakening of the adaptive immune system plays a role in why we have an increased likelihood of getting cancer as we age. 

“One of the most dramatic changes with age, and the most sizable and robust physiological changes with age that we see, is that your sleep gets worse,” explains Matthew Walker. “And sleep is probably one of the most powerful regulators of your immune system.”

This UCLA study(9) shows how even partial sleep deprivation reduces natural killer cell activity, which zeroes in on foreign elements like cancer cells and destroys them, in humans by 70%. Just imagine what kind of damage months of sleep deprivation could do.

There is also overwhelming evidence linking sleep deprivation to cancer of the bowel, prostate and breast – which make up three of the four most common types of cancer. In fact, the causal evidence is so strong that the WHO has classified night shift work as a ‘probable carcinogen’(10).
We delve into whether sleep deprivation can escalate the risk of certain diseases in our next article. For more solution-oriented articles to do with sleep, go through our tips for getting a good night’s sleep and whether we could maybe flip the script and use technology to improve sleep quality.