Your life depends on your ability to sigh.

Yes, we sigh when we're exhausted or stressed — and when the weight of the world feels like too much to bear — but it turns out that sighing is also an essential life-sustaining reflex that is necessary to keep our lungs from collapsing.

Researchers from the University of California, Los Angeles, and Stanford University describe the neural circuitry of sighing for the first time as well as pinpoint the exact location in the brain from which our sighs originate.

Most humans heave an involuntary sigh an average of 12 times an hour, said Jack Feldman, a professor of neurobiology at UCLA and a senior author on the paper. These types of sighs are not related to emotion, Feldman said. Instead, they provide an extra gust of air that helps to reinflate some of the 500 million tiny balloon-like sacs in our lungs called alveoli.

When they collapse, the only way to pop them open again is to sigh, which brings in twice the volume of a normal breath, Feldman said.

Depression screen urged for ages 12 and up

Amid evidence that fewer than half of depressed adolescents get treatment for their emotional distress, a federal task force has recommended that physicians routinely screen children between 12 and 18 for depression and have systems in place either to diagnose, treat and monitor those who screen positive or to refer them to specialists who can.

The new recommendations, issued by the U.S. Preventive Services Task Force, bring depression screening for adolescents into line with recently issued depression-screening recommendations that apply to adults.

Collectively, the new guidelines mean that virtually all Americans older than 12 will be checked periodically for persistent signs of sadness or irritability, changes in sleep, energy and appetite, or feelings of guilt or worthlessness.

Obama seeks $1.1B for drug abuse

President Obama called for $1.1 billion in new federal money to combat the growing abuse of heroin and prescription painkillers in the U.S.

Most of the proposed new money — $920 million — would fund cooperative agreements with states to provide more drug-based treatment for people addicted to painkilling opioids such as OxyContin, Percocet, hydrocodone and morphine.

From 2010 to 2012, the death rate from heroin doubled across 28 states that represent 56 percent of the U.S. population, according to a 2014 government report.

Long hours does not hurt patients

Allowing surgeons in training to work extremely long shifts without breaks had no effect on patient outcomes and created only minor dissatisfaction among the young doctors, research shows.

Patients' rates of death, serious illness, infection, pneumonia and most other common postoperative complications were no worse in hospitals that permitted the novice doctors to work longer stints for the purposes of the nationwide study than in hospitals that limited work hours.

The residents said they valued the chance to follow patients for more than 28 hours because of what they learned and did not think that such shifts jeopardized their own health. Some research has suggested that the practice places physicians at higher risk for depression, sleep problems and trouble concentrating. The physicians acknowledged that the extended shifts did have some effect on their lives outside the hospital. "But they are professionals," said Dr. Karl Bilimoria, the main author and a professor of surgery at the Feinberg School of Medicine at Northwestern University, "and they are making this trade-off."

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