Harms your immune system
Studies show that all it takes is one night of sleep loss to increase the amount of toxins in your body, putting you at risk of illnesses like cancer and heart disease. Sleep allows your body to repair injuries, replace dead cells, and preserve muscles and vital organs. It also maintains your immune system. Dr Eric Hong, medical director of EH Heart Specialist at Mount Elizabeth Medical Centre, explains that sleep deprivation stresses the body, which in turn, stresses the heart.

Raises your blood pressure
Dr Hong shares that if you suffer from hypertension – a  condition where your blood pressure is chronically raised – and don’t sleep enough the night before, your blood pressure goes up the next day. This stresses your blood vessels, causing them to weaken and clog up. Narrowed blood vessels are more likely to get blocked by blood clots, or by bits of fatty material that break off from the blood vessel wall. Over time, this can lead to heart disease.

Upsets your hormones
Lack of sleep affects the hormones that control your appetite, metabolism and how your body breaks down complex carbohydrates such as whole grains and vegetables, into glucose. “Poor sleep leads to an increase in cortisol, a stress hormone,” says Dr Hong. When your cortisol level goes up, blood pressure can spike.

An increased cortisol level also affects how your body controls blood glucose levels. If your body isn’t processing blood glucose well, you’re more likely to store fat and gain weight, which increases your risk of diabetes. If you are diabetic, your risk of heart disease goes up, as it’s associated with high blood pressure, abnormal cholesterol levels and obesity. 

Leads to hypertension
You may not be getting quality rest at night if you have obstructive sleep apnoea (OSA). “Sufferers typically wake up multiple times each night because their airways tend to close when they fall asleep, so they briefly stop breathing,” says Dr Hong. “They experience chronic fatigue and surges in blood pressure each time they wake up.” If left untreated, OSA can lead to hypertension – a major risk factor for cardiovascular disease. But once it is treated, your blood pressure can go down, reassures Dr Hong.

How much sleep do you need for your heart? 
Dr Hong says that according to a study, sleeping too little (less than six hours) raises the risk of heart disease in women by up to three times. Interestingly, the same study showed that sleeping too much (more than nine hours) also increased heart disease risk, although researchers say that more studies are needed to explain why this is so. 

This article was originally published in Simply Her April 2013.