Strange as it might seem, too much information can make a health problem worse.

Take the case of sleep-tracking apps. A meticulous record of insomnia can itself produce sleepless nights.

It’s one of the best-attested facts in medicine that believing we will get better helps us both feel and get better (the placebo effect). And believing we will get worse tends to make us feel and get worse (the nocebo effect).

Believing we are at risk (or not) makes a difference too, as one striking experiment showed:

A stunning example of how the mind shapes our physiology emerged from a recent Stanford University study of how people react to learning about genetic risk factors. About 200 study participants took genetic tests and were told that, based on the results, they were either at risk of or protected from two obesity-related factors: cardiorespiratory (heart-lung) exercise capacity or satiety (feeling full) after eating. In fact, they had been assigned to the different groups randomly.

The news changed their physiology to match what they were told. Regardless of their actual DNA-based risk, they had more or less lung capacity and endurance when exercising and more or less of a hormone that makes people feel full.

Michele Cohen Marill, “Why Tracking Your Symptoms Can Make You Feel Worse” at Wired

Yes, under certain circumstances, thinking does make it so:

“It’s interesting that in the exercise study we saw a negative effect for those who were told they had the high-risk version, but in the eating study we saw a physiological improvement in people who were told they had the protective gene,” Turnwald said. “What was consistent in both studies was that those informed that they had the high-risk gene always had a worse outcome than those informed that they had the protective gene, even though we essentially drew out of a hat which information people received.”

Those differences between groups were in some cases even stronger than the real differences they saw as a result of people’s actual genetic results. All this underscores the fact that the act of receiving genetic information and the resulting mindset can have as much of an impact as the genes themselves in some instances, according to Crum.

Amy Adams, “Stanford researchers found that receiving genetic information can alter a person’s risk” at Stanford News

All these results are consistent with the fact that the mind is real, not an illusion; it acts on the body just as the body acts on the mind.

Put another way, what we think is happening to us is an inescapable part of what is happening to us.

It’s good to get the best information available. But the process of getting that information helps shape our minds. Our minds in turn help shape our bodies. So an obsession with health tracking apps can become part of the very problem the apps were meant to address.

Even before apps were as widely used, drowning in online information was having the same effect:

Going online to search for health information may not be a good idea for people who fear uncertainty, according to a new study.

For these people, the false belief that they suffer from a serious disease (hypochondria) can worsen as they scour the Internet in an attempt to pinpoint symptoms, a Baylor University researcher found…

Although people having unfounded fears about health is not new, the overwhelming amount of online medical information may be more disturbing than what people read in medical manuals or get directly from a doctor.

Robert Preidt, “Too Much Online Health Info May Worsen Worriers’ Anxiety” at Healthday

In the Information Age, we face a problem our ancestors did not face: far too much information. Many of us have better skills for dealing with uncertainty than with information overload. Our challenge is learning how to know when we have all the information we need to calmly make decisions we can live with.

Note: More about Baylor researcher Thomas Fergus’s study here.

See also: Yes, the placebo effect is real, not a trick