If sexual health depends upon knowledge, a lot of kids these days may be in trouble.

A new federal study reports that fewer than half of U.S. high schools and only one-fifth of middle schools teach all 16 topics of sexual health recommended by the Centers for Disease Control and Prevention.

State-by-state percentages ranged across the board, from a low of 21 percent of high schools mandating courses in Arizona to 90 percent in New Jersey. (Only New York and New Hampshire were also above the 75 percent mark.)

The proportion of middle schools requiring all 16 topics ranged from 4 percent (again in Arizona) to 46 percent in North Carolina. In no state did more than half of middle schools meet the goal; in most states, it was less than 20 percent.

Examples of topics include prevention of HIV, sexually transmitted diseases and pregnancy.

"We need to do a better job of giving our young people the skills and knowledge they need to protect their own health," said Dr. Jonathan Mermin, director of the CDC's National Center for HIV/AIDS, Viral Hepatitis, STD and Tuberculosis Prevention. "It's important to teach students about healthy relationships and how to reduce sexual risk before they start to have sex."

Body of Knowledge

To avoid being bogged down by random signals, our brains require that at least five to 10 photons (particles of light) hit our retina in the span of 10 microseconds (one millionth of a second) to be consciously registered as light.

Get Me That, Stat!

An estimated 44 million Americans live in households that have trouble paying their medical bills, according to the CDC. That's actually good news of a sort: The share of people under age 65 in families struggling to pay for health care has dropped from 21 percent in 2011 to 16.5 percent. One-third of those who struggle to pay are uninsured; another 20 percent are covered by Medicare or Medicaid.

Life in Big Macs

One hour of hanging storm windows burns 704 calories (based on a 150-pound person), or the equivalent of one-half of a Big Mac. Or 4.3 3.5-ounce glasses of wine (not to be consumed until the job is done).

Counts

78.8: average life expectancy (years) in U.S., unchanged from 2013.

1: percentage decrease in the age-adjusted death rate, to 724.6 deaths per 100,000 standard population from 731.9 percent in 2013.

582.1: number of infant deaths per 100,000 live births in U.S., down 2.3 percent and a new historic low (though still much higher than most developed countries).

Source: CDC/NCHS, National Vital Statistics System, Mortality

Stories for the Waiting room

Diacetyl is a chemical that's been linked to serious respiratory problems and lung disease. In a bit of unhappy irony, new research out of Harvard reports it's also found in more than three-quarters of flavored liquid nicotine — the stuff used in e-cigarettes.

Doc Talk

Q: Text shorthand for "every iteration." For example, Q5min would mean once every five minutes or Q6h would be once every six hours.

Phobia of the Week

Genuphobia: fear of knees.

Hypochondriac's Guide

Parry-Romberg syndrome is a rare affliction characterized by progressive shrinkage and degeneration of tissues beneath the skin, usually on just one side of the face. The precise cause isn't known, but it is believed to be acquired disorder and may be associated with autoimmune dysfunction. The syndrome affects females more than males, usually appearing between ages five and 15. Treatment may involve immunosuppressive drugs and surgery.

Observation

"After you find out all the things that can go wrong, your life becomes less about living and more about waiting." — author Chuck Palahniuk in "Choke"

Medical History

This week in 1845, Crawford Long of Jefferson, Ga. used ether for the first time in childbirth, applying the anesthetic to his wife, who successfully gave birth to a baby girl. Three years earlier, Long had administered inhaled ether to James M. Venable for the removal of a tumor from his neck. It was the first documented use of surgical anesthesia.

Self-Exam

How many dreams does the average person experience each night?

1) 1-2

2) 3-6

3) 4-7

4) 9-10

Answer: Most people dream approximately one to two hours a night, and average 4-7 dreams each night (not that they necessarily remember all of them later).

Medical Myths

Remember when you mom told you not to swallow your gum because it would stick around in your stomach for seven years? It sounded dubious then too, even with the very specific time frame. It is true that gum contains indigestible ingredients, such as elastomers, resins and waxes, but they don't linger in your gastrointestinal tract any longer than Aunt Susie's equally indigestible Christmas fruitcake. It all comes out in the end, sooner than later.

Curtain Calls

In 1994, 16-year-old Jeremy Brenno of Gloversville, New York, was killed when, after an errant shot, he angrily smashed his club against a nearby bench. The club shaft broke, bounced back and fatally impaled him in the chest. It was a No. 3 wood.

To find out more about Scott LaFee and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.

Photo credit: Ryan Dickey