Sleep issues are an increasing problem in Australia, with up to 45% of adults not getting as long or good rest as they need each night.

It's World Sleep Day on Friday, March 19 and new research from Blackmores shows high stress levels are also keeping Aussies awake at night. The Blackmores Stress & Sleep research revealed almost two thirds (65%) of Aussies admitting their stress often negatively affects the quality of their sleep, with nearly a quarter (23%) contacting a health professional or attending hospital in the last year because of stress.

While you’re probably aware of some of the issues that result from sleeplessness, like mental fog, that can arise when you don't get enough rest, you may not be aware that your snoozing habits may impact all sorts of unexpected things - think: how well your heart pumps blood, and even your sex drive.

“Most of the systems in our body are predicated on some process of renewal or need for sleep,” explains board-certified sleep medicine researcher Dr W. Christopher Winter the author of The Sleep Solution: Why Your Sleep Is Broken and How to Fix It. “Sleep is a fundamental aspect of our thinking, our ability to function, and our immune system. It impacts pretty much everything we need to survive.”

So make a resolution to turn off your phone, close the shades, and hop into bed early in 2021. If you don’t, here’s how a lack of sleep may impact your body.

1. It can hurt your immune system

“There’s a very strong link between sleep and the immune system in general,” says Dr Michael Awad. “The body repairs just about every cell in the body when it comes to sleep. Sleep deprivation lowers the body’s ability to mount an immune response.”

Sleep loss is linked to a higher risk of infection. One study published in JAMA found that restricting a person’s sleep for four hours a night for six days, followed by sleeping 12 hours a night for seven days, can lead to a greater than 50% decrease in the production of antibodies to a flu vaccine. Basically, your body just can’t mount the usual immune response when you’re wiped out.

Lack of sleep can also lower your immune system’s ability to fight tumour cells and lead to the generation of inflammatory cytokines. These proteins are secreted by the immune system and can cause the development of metabolic and cardiovascular disorders.

2. It can raise your risk of heart disease

One study of nearly 117,000 people published in the European Heart Journal found that people who slept less than six hours a night were at a greater risk of developing heart disease than their well-rested counterparts. And getting irregular sleep—that is, having no consistent bedtime and wake time—can raise your risk of having some kind of cardiovascular event, including stroke, congestive heart failure, and coronary heart disease, according to a study published in the Journal of the American College of Cardiology.

There are a “tremendous number of mechanisms” at play here, Dr Winter says. “When you are sleep deprived or have fragmented sleep, your blood vessels lose, to some extent, the ability to expand and contract to regulate things,” he says. People also tend to be at a higher risk of developing high blood pressure when they don’t get enough sleep, Winter says, which can be tough on your heart.

Sleep deprivation can also increase cholesterol levels and general inflammation throughout your body, leading to the formation of plaque in the blood vessels, Dr Awad says. “When blood vessels start to form plaque, the heart has to work harder,” he explains.

3. It can lower your sex drive

There are a lot of reasons for this, Dr Winter says. “When you’re fatigued, your brain prioritizes getting sleep over other things,” he says. But Dr Winters says other chemicals that are important for sexual performance and arousal, such as oxytocin, can be lowered by sleep deprivation.

One study in JAMA restricted 10 men's sleep for a week and found that the levels of the sex hormone testosterone in their bodies decreased by up to 15%. (Testosterone is a hormone that can fuel a person's sex drive.) The reverse is also true: Another study published in JAMA found that people who got more sleep than usual were more likely to have sex the next day. Meaning, if you hit the hay earlier, you just might be up for a little something extra.

4. It can raise your risk of weight gain

There are a few reasons for this. One is that people “tend to make bad eating decisions when they’re tired,” Dr Winter says. People are also typically more sedentary and less likely to work out when they’re tired, which also can lead to weight gain, he says.

Research published in the journal Sleep found that people with restricted sleep had altered levels of endocannabinoids, one of the chemical signals that affect appetite, and the brain’s reward system. The researchers also discovered that when people were sleep-deprived, they ate more and unhealthier snacks between meals, at the same time that endocannabinoid levels were at their highest.

Older research has also found that women who get less sleep tend to weigh more than their better-rested counterparts, likely for the reasons above, Dr Winter says.

5. It can increase your risk for developing diabetes

There’s a direct correlation between lack of sleep and diabetes, Dr Awad says. It’s due to your body’s ability to regulate insulin, a hormone produced in the pancreas that controls your blood sugar, he says. “Lack of sleep reduces the production of insulin from the pancreas and decreases gluten tolerance,” Dr Awad says. “Cells are then less effective at using insulin, and that can lead to the development of diabetes.”

To be clear: Sleep deprivation isn’t cited by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) as a potential cause of diabetes, but insulin resistance—which can be caused by lack of sleep—is.

How to finally get more shut-eye

If you’re struggling with sleep, Dr Winter recommends first trying to prioritise rest and practicing good sleep hygiene. That includes the following:

  • Go to bed at the same time each night and get up at the same time each morning, including on weekends.
  • Make sure your bedroom is quiet, dark, relaxing, and at a comfortable temperature.
  • Remove electronic devices, such as TVs, computers, and smartphones, from your bedroom.
  • Avoid large meals, caffeine, and alcohol before bed.
  • Exercise regularly. Being physically active during the day can help you fall asleep more easily at night.

If these tried-and-tested tips don’t help, Dr Awad says it’s a good idea to talk to your doctor about what else you can do to get the rest your body needs.