In your hectic, daily schedule, sleep can seem like such a hindrance – that’s eight hours of your day in which you’re not doing anything productive! However, sleep is actually extremely productive for your overall wellbeing. Sleep helps you to stave off major health concerns by aiding your mental and emotional wellness, keeping you trim, strengthening your immune system, fighting inflammation, and maintaining your heart and blood vessels.
In fact, sleep enables your body to repair your damaged tissues, produce crucial hormones and strengthen your memories. This latter process is known as consolidation, and it helps you to perform a new skill better after sleeping than you would if you spent an equivalent amount of time awake, which is why all-nighters are never as effective as you think they’ll be. Virend K. Somers, MD, a professor of medicine and cardiovascular diseases at the Mayo Clinic in Rochester, Minnesota, who studies sleep and heart health, explains, ‘It’s a way for the body to integrate everything that happened over the past waking day and to kind of prepare for the next day.’
According to Shelby Freedman Harris, PsyD, director of behavioural sleep medicine at Montefiore Medical Centres Sleep-Wake Disorders Centre in New York City, ‘When you’re sleeping you’re regulating hormone levels, you’re regulating insulin levels, your blood pressure is being kept under control, there are a lot of things going on, and if you’re not getting enough sleep you’re throwing these things out of whack.’ One way in which your body becomes skewed by a lack of sleep is in your heart. If you get less than six hours of sleep a night, or you don’t spend enough time in the deepest stages of sleep, you have a higher risk of heart attacks and strokes than those who get at least seven hours.
In 2011, two studies revealed the devastating impact of sleep deprivation on heart health. The first study, performed in male Japanese factory workers, showed that sleeping for less than six hours a night made the factory workers five times more likely to have a heart attack over a 14-year span compared with those who logged between 7 and 8 hours a night. The second study, this time involving men over the age of 65, showed that even healthy participants with normal blood pressure were almost twice as likely to develop hypertension if they spent less time in the deepest sleep stage (known as slow-wave sleep).
As well as long-term sleep deprivation having an impact on your heart health, there’s also some evidence – albeit somewhat limited – that even short-term sleep deprivation may be harmful if you already have a heart problem. Swedish researchers, who published the results of their work in 2012, reported that in the week after the spring transition to daylight saving time, hospital admissions for heart attacks increased by about 4% compared to other weeks. This is the time in which you set your clocks an hour ahead and lose an hour of sleep.
As to why not sleeping enough affects your heart, wellness experts aren’t quire sure. However, researchers are clear on why sleep apnoea is a known heart hazard. If you have sleep apnoea, you tend to snore and have upper airway collapse during sleep, meaning that you snort and gasp for breath without really waking up enough to be aware of it. Charles Czeisler, MD, the Baldino Professor of Sleep Medicine at Harvard Medical School in Boston, explains, ‘It’s as if somebody’s choking you, so your heart rate goes up, your blood pressure goes up, and instead of having a daily cycle in which everything slows down at night, instead everything is higher during the night. Over time, even your daytime blood pressure is higher.’