King David promised to “awaken the dawn” and offered elsewhere in the Psalms that he would “both lie down in peace, and sleep.” Plenty of us are doing the former, but many of us aren’t doing enough of the latter: According to a 2012 report in the journal Sleep, “approximately 1 in 3 adult Americans are sleeping less than 7 hours per night.”

The report describes the medical risks of accumulating a sleep debt, from heart attacks and obesity to cancer. The most immediate risk is obvious: We drive and operate machinery poorly when we’re tired. One study found that “drowsy driving” played a role in up to 20 percent of traffic accidents. Another likened the effect of sleep deprivation to driving drunk.

So how much sleep do we need? As parents with young children know, it varies with age: The National Sleep Foundation advises an average of 14 to 17 hours per day for a newborn, with as few as five being appropriate for certain older adults. For the average adult, the foundation recommends seven to nine hours.

All hours of sleep are not the same. Everything from city noise to stress can interrupt sleep, leaving a person groggy the next day. One common medical cause is sleep apnea, where a sleeper’s airway temporarily closes—forcing him to wake up, sometimes hundreds of times per night, to take a breath. It’s most common in heavy snorers, especially those who punctuate their snoring with gasps or pauses, and the most obvious result is frequent sleepiness during the day without any other obvious cause. Treatments include weight loss and continuous positive airway pressure (CPAP) machines; for patients who can’t tolerate CPAP, experimental treatments include a specially fitted mouthpiece designed to pull the lower jaw slightly forward.

Sleep apnea deserves professional evaluation, but not all sleep troubles need such measures: Sleep hygiene—the term refers to ways people can protect their sleep, not to showering and putting on clean pajamas—is a series of commonsense recommendations that help many people sleep more soundly. They include not drinking caffeine in the afternoon or evening, avoiding food and TV in bed, and establishing a dark, quiet environment in the bedroom.

Research also appears to establish a link between bright lights—think TVs, computer screens, and smartphones—in the hour before bedtime and dips in the body’s level of melatonin, a hormone that regulates sleep. Between online activity and the stimulation of the screen itself, a 2014 study by the National Sleep Foundation found that children with tablets or smartphones in their bedrooms averaged almost an hour per day less sleep than those without. Mom was right: We sleep best when we turn our toys off at bedtime.

Pricing puzzle

Deflazacort Handout

The FDA recently approved the steroid deflazacort to treat Duchenne muscular dystrophy, a rare but devastating disease that robs children of muscle strength. The drug sells for about $1,200 a year in Canada, so the planned U.S. list price of $89,000 per year reignited debates both about pricing and about what to do in response: Importing it is now technically illegal, but the FDA has not prosecuted patients importing small quantities for their own use. (The drug itself could be seized at the border.) Drugmaker Marathon’s original pricing strategy apparently was to establish a very low price for individuals while charging insurers top dollar. In the face of public outrage, though, Marathon has sold its rights to the drug. The new owner, PTC Therapeutics, has not yet named a price. —C.H.