Recently, Lady Gaga announced "I'll sleep when I'm dead." She got it exactly backwards. Any animal sleep deprived long enough will die.
But what about people? Americans are sleeping 90 minutes less than 40 years ago, and working hard to shave off more time. Can the partial sleep deprivation of insomnia affect survival?
If we believe the results of the Wisconsin Cohort Study, yes. Chronic insomniacs, when other chronic diseases were controlled, died at more than twice the rate of those with fewer symptoms.
Civil Servants Can't Sleep
Professor Terry Young and company have been doing excellent sleep population studies a long time. Starting in 1989, then again in 1994 and 2000, they asked 2200 Wisconsin state workers about health and sleep. People who answered positively on more than two separate occasions were considered chronically insomniac. A whopping 46% fit criteria, a loose definition that usually makes it hard to find an effect.
If someone is chronically ill they will report insomnia far more frequently. The way to statistically control these results is to adjust for chronic diseases like diabetes and heart disease, as was done by Young and colleagues. Yet the procedure is far from foolproof. A full generation of doctors learned from the landmark Nurse's Health Study that hormone replacement therapy markedly decreased cardiovascular deaths.
That finding turned out to be dead wrong. The people who had adopted HRT were proactively health conscious women, and their inclusion fatally biased the results. The Wisconsin researchers did the standard things to fix their data, and their insomnia results held up. So what's going on?
People Who Sleep Too Little
It's been known for a long time that people who sleep too little, on average less than 7 hours, have greater mortality. They include groups that habitually sleep less - like shift workers, people with mood disorders, and now a huge number of working women. The increased death rates are thought to result because diseases not yet diagnosed somehow disrupt sleep.
What was missing from the Wisconsin data are statistics on sleep disorders and depression. Sleep disorders usually sort together with many other illnesses that were checked, like high blood pressure and diabetes - if you have these illnesses, chances are higher you'll have sleep disorders like sleep apnea.
Depression is another story.
Those Who Can't Sleep
In the Wisconsin data, the "odds ratio" of higher death rates occurred around two questions - frequent and early awakenings. Those who awakened frequently had 3.2 times the expected rate of death, and those who woke early 2.4 times the expected rate.
Both symptoms are commonly seen in major depression. It's also been known for a long time that chronic insomniacs, especially after 10 years of symptoms, have higher depression rates. Regardless of cause and effect, those who long sleep poorly tend to get depressed.
How Does Lack of Sleep Kill?
Depression is really bad for your health. Besides suicide, depression causes many people to lose jobs, family and social support, and not engage in healthy behaviors. But lack of sleep causes many other problems. A recent West Virginia University showed that people sleeping less than five hours a night had twice the expected death rate. Sleeping less than six hours is strongly related to weight gain, getting more infections, markedly increased risk of coronary calcification, and poor learning. The body does a lot of its rebuilding in sleep.
So it really does look like sleeping less is hazardous to your health - and your survival.
What Is To Be Done?
Insomniacs need treatment, most of which should be behavioral. Yet everybody needs enough sleep. Routinely I talk to people who tell me their jobs, sometimes multiple, are making them get 5 hours or less sleep each night. They're tired all the time, and feel exhausted when they want to feel happy, like when playing with their kids.
And they may be shortening their lives. Rest is restoration. It's also rebuilding, renewal, and revitalization. Our model of disease, where the machine just breaks down, may be the wrong one. The real model may be that illness occurs when our normal rest-rebuild process is corrupted or delayed. With insufficient rest, including sleep, we may not properly replace most of our hearts in three days, like we do now; or redo our guts in a few days; or reset our immune system to deal with its many threats.
Rest is as vital as food to our body's healthy rebuilding. We love to eat, we love food. It's time to learn to love rest, too. We need it to survive.