By Mary Carpenter
At the same time readers were asking for an updated post on sleep, Well-Being Editor Mary Carpenter got a book recommendation—in a random conversation with a physiatrist, who was listening to it with his son—of Why We Sleep, by Matthew Walker. It challenged her assumption there could be very little new to read on the subject.
HIGHLIGHTING the spectacular achievements of the sleeping brain, Walker traces “society’s apathy toward sleep [in part to] the historic failure of science to explain why we need it”—and explains why each person benefits from paying close attention to their body’s unique natural sleep schedule. He concludes, however—acknowledging that some people need wake-up alarms to stay in synch with the rest of the world–with advice for those people struggling to do that, along with measures beneficial to everyone, called “sleep hygiene.”
Insufficient sleep “disrupts blood sugar levels so profoundly that you would be classified as prediabetic, [and] physical and mental impairments caused by one night of bad sleep dwarf those caused by an equivalent absence of food or exercise,” writes Walker. Referring to the CDC position that “most adults need at least 7 hours of sleep each night,” Walker explains that too little sleep also “appears to be a key lifestyle factor linked to risk of developing Alzheimer’s disease.”
Setting an alarm to wake two hours early means “you may lose 60 to 90 percent of all your REM sleep,” Walker writes.” Or, if you “don’t go to bed until 4am, then you will lose a significant amount of your normal deep NREM sleep [with an effect similar] to an unbalanced diet.” NREM refers to the four non-rapid-eye-movement stages of deep sleep that occur within each 90-minute sleep cycle—and that ends with the fifth, rapid-eye-movement (REM) stage of dreaming. But the increased length of REM stages within each cycle throughout the night—along with longer NREM stages in the hours after falling asleep—create the disproportionate loss linked to curtailing sleep at either end.
Think of “NREM sleep as reflection (storing and strengthening those raw ingredients of new facts and skills [garnered during the wake state], while the wake state is “reception (experiencing and constantly learning the world around you),” writes Walker. He considers NREM sleep “one of the most epic displays of neural collaboration that we know of. Through an astonishing act of self-organization, many thousands of brain cells have all decided to unite and ‘sing” or fire in time.”
And think of REM sleep as “integration (interconnecting these raw ingredients with each other, with all past experiencing, and in doing so building an ever more accurate model of how the world works, including innovating insights and problem-solving abilities),” he writes. In a sleep lab, measurements of eye movements during each stage help assess the quality of an individual’s sleep—with those during REM periods reflecting the “movement-rich experience of dreams.”
“Morning larks” make up about 40 percent of the population, according to Walker, with “night owls” accounting for some 30 percent. The remaining 30 percent fall somewhere in between larks and owls “with a slight leaning toward eveningness. …most unfortunately, owls are more chronically sleep-deprived [with] greater ill health…including higher rates of depression, anxiety, diabetes, cancer…”
Of two factors that affect sleep schedules, one is the familiar 24-hour circadian rhythm—which responds to environmental factors, including light, food and exercise. “Sleep pressure” is the other, increasing throughout the day as the chemical adenosine builds up in the brain. But this buildup can respond to artificial muting, for example, by caffeine—which Walker calls “the most widely used (and abused) psychoactive stimulant in the world.”
No sleeping medication induces “natural sleep,” in Walker’s opinion. He explains that older, sedative hypnotics, such as diazepam, “sedated you rather than assisting you into natural sleep.” And newer drugs, including Ambien and Lunesta, create sleep that lacks the largest, deepest brain waves—and often come with side effects that include next-day grogginess and forgetfulness.
Cognitive behavioral therapy for insomnia, CBT-I—the remedy currently deemed “the most effective,” according to Walker—offers each patient a “bespoke set of techniques.” Number one for most people is sleep restriction—also called sleep consolidation —limiting time in bed, often starting with six hours or less. Explains Walker, “by keeping patients awake for longer, we build up a strong sleep pressure—a greater abundance of adenosine …patients fall asleep faster and achieve a more stable, solid form of sleep across the night.”
Sleep-restriction goals start by using the hours of actual sleep recorded in a sleep lab—for example, five hours of deep sleep out of the seven or eight spent in bed. A 2015 meta-analysis of CBT—that included 1,162 patients—found improvements in total sleep time and sleep efficiency by eight to ten percent, reported in the Annals of Internal Medicine—with the note that “psychological approaches are likely to produce sustained benefits without the risk for tolerance or adverse effects associated with pharmacologic approaches.”
With CBT-I —“generally…the first treatment recommended,” according to the Mayo Clinic, the cognitive component “teaches you to look for and change beliefs that affect your ability to sleep…help you control or get rid of negative thoughts and worries that keep you awake.” One recommendation is to “remain passively awake”—by suppressing thoughts about falling asleep.
“Stick to a regular sleep schedule. Go to bed at the same time each night and get up at the same time each morning, including on the weekends “is the number one recommendation from the CDC and elsewhere for “sleep hygiene”—suggestions that apply to everyone, regardless of sleep challenges. Also on most lists: “take a hot bath before bed;” and the familiar “don’t lie in bed awake” — instead, get up for a while.
Following a sleep schedule helped Connecticut organic farmer L.P. who had battled insomnia for decades using various methods and medications—but the most effective for her was sleep restriction. Having known L.P. since childhood, I was relieved she’d finally found something that worked better than drugs—with their risks of side effects and of increasing tolerance that included her inability to sleep without them. And because I cannot wake without an alarm, what I appreciated most about Walker’s book was his description of sleepers like me—who fall somewhere between larks and owls—and have “a slight leaning toward eveningness.”
—Mary Carpenter regularly reports on topical subjects in health and medicine.