What is a meta-analysis? A meta-analysis (MA) is a mathematical method of analyzing the results and conclusions of a broad array of different studies on a specific subject. Meta annalists arrive at conclusions based on complicated formulations that work through a vast body of data using methodologically sound studies.
Recently meta analysts have been crunching the data on premature death and sleep. For instance, do studies indicate that a lack of sleep causes early death? Or, do they indicate that too much sleep causes premature death? Some studies indicate a yes. Others indicate no. Which is it? Could it be both?
How can good studies have it both ways? Perhaps sleep duration isn’t even a good predictor of length of life? To be sure, all studies have errors. Some are tiny, some are huge. This is where the meta analysts come in. They seize the results of all of the studies, all of the concrete-discreet revelations, and scrutinize the data in search of a fundamental common truth.
It is not secret that statistics are tricky and can be manipulated to say just about anything, but can they honestly extrapolate conclusions from studies that show conflicting results. In one MA of sixteen studies about sleep and life expectancy they looked at the data on one million three hundred thousand subjects. They concluded that early death occurred to people who got less than 6 hours of sleep per night. Based on that figure they concluded that 12% of people not getting enough sleep were likely to die a premature death.
This claim is totally contrary to earlier research published in the same journal. That research concluded that 30% of the individuals who slept more than 10 hours (or longer) were probably going to live to be 100. So, do people live to be 100 because they sleep for 10 hours per night or should they sleep 10 hours per night because they are healthier?
Ultimately how well and how long you sleep is a litmus test for mental and physical health. Sleep is essential for longevity. Getting too much sleep may indicate that you are not in the best health. Getting too little sleep may also indicate that you may also not be in good health. But in terms of life longevity, the data does not suggest that too much or too little is necessarily bad.
To derive a pooled estimate analyst ultimately could not conclude one way or the other which left them with no choice but to choose the middle ground, meaning that to live a long good life you should get seven to eight and a half hours of sleep in a twenty-four-hour period.