Doctor's Review: Medicine on the Move

January 22, 2022
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In search of a perfect sleep

New research suggests shorter sleeps depend on temperature

“Sleep is the new sex” was an off-the-cuff declaration that appeared widely in the media in the early 2000’s. People found it funny because, true or not, it rang true for many. With one in three North Americans experiencing some form of insomnia and many more burning the candle at both ends, sleep seemed a luxury, a pleasure greater than even the sacred pinnacle of bodily delights. And when it comes to overall health, good sleep is more important than good sex. Abstinence lacks the health risks associated with sleep deficits: heart disease, obesity, depression, lack of mental clarity, accidents in the work place and on the road.

Sleep science, and especially sleep medicine, is young. Rapid Eye Movement (REM) sleep — the kind of sleep that occurs at intervals during the night and is characterized by rapid eye movements, more dreaming and bodily movement, and faster pulse and breathing — was discovered just half a century ago. Only in the past 25 years has there been an organized study of sleep through organizations like the US-based Sleep Research Society and the Canadian Sleep Society and others. Though the function of sleep still retains some of its mystery, current ideas suggest that it clears the brain of compounds that build up during the day and is also a time when short-term memories are moved to long-term storage.

Mice die after about 20 days without sleep. Though no humans have volunteered for these sorts of studies, an American high school student named Randy Gardner tried to break the record for the longest time awake in the 1960’s, ending the experiment after 11 days and 24 minutes with slurred speech and an expressionless appearance. The Guinness Book of Records was so alarmed by the effects on Gardner that they stopped listing records for voluntary sleep deprivation. In October 2010, 28-year-old L.A. celebrity photographer Tyler Shields claimed to have gone 40 hours without sleeping, but his feat has been largely written off as an unproven publicity stunt.

Death by lack of sleep

Sepsis was the cause of death for the mice who died of sleep deprivation, reinforcing data from sleep studies of humans whose immune systems begin to fail when they don’t get enough sleep. Disruption of sleep in intensive care units due to environmental light and noise as well as patient care interactions has been found to lead to an increase in sepsis. Lack of sleep also interferes with the effectiveness of vaccines, resulting in the production of half as many antibodies than when in a well-rested state. On the other hand, some members of the medical establishment seem to doubt the dangers of sleep deprivation. In the US, despite a mounting number of studies that point to the dangers to patients of depriving doctors who treat them of sleep, the maximum allowable workday for first-year medical students just rose from 16 to 28 hours.

Powerhouses in politics and entertainment have also served as poor examples of sleep hygiene, instead bragging about how little sleep they need — their "sleep machismo" number. Current US president Donald Trump may be among what’s known as the “sleepless elite,” the one to three percent of the population that requires very little sleep owing to a genetic mutation. Margaret Thatcher, Jay Leno and Barak Obama are also famously short sleepers, requiring less than six hours a night. How do you know for sure if you’re among the sleepless elites or just under-slept? If you have the opportunity to sleep more than six hours and you take it to pick up an extra hour or two of shut-eye, then you are probably a regular human. True members of the "sleepless elite," are those who have a tiny mutation in a gene called hDEC2. They never sleep more than a few hours, even if they have ample opportunity, and are characterized by sunny dispositions and a lack of need for naps and are often thin.

So what about the rest of us? Is the prescribed seven to nine hours really necessary? And where did the holy grail of virtuous sleepers — the magic number eight — originate? The classic teaching that adults need seven or eight hours of sleep seems to be supported with scant evidence. It is probably a relic from the late 18th century, when industrialization was running factory workers ragged and a Welsh social reformer named Robert Owen stepped in to save them from the 16-hour work day by declaring, “Eight hours labor, eight hours recreation, eight hours rest.”

Sleep expert Dr Daniel Kripke, co-director of research at the Scripps Clinic Sleep Center in La Jolla, California says the eight-hour figure was derived from population studies showing sleep averages. He asserts that people who report sleeping 6.5 to 7.5 hours per night live the longest, though he admits that the reasons why have yet to be proven, let alone whether the habits of those people would be healthy for everyone. Dr Kripke claims that sleeping too much may be just as damaging to one’s health as sleeping too little, saying that an 8.5 hour sleep schedule could be worse for you than getting a mere five hours of shut-eye a night.

Seven hours of shut-eye best?

Sleeping less than seven hours in a 24-hour cycle may be more natural than we’ve been conditioned to think. It isn’t just fast-living urbanites who are out for six or so hours a night. According to a recent study, individuals in existing hunter-gatherer societies in Africa and South America spend about seven or eight hours a night in bed, but they only sleep five to seven of those hours — on the low the low end of what urbanites sleep. Most of us have been trained to believe that if we’re under the seven-hour mark we must have insomnia and are doomed to poor health. But insomnia and other health problems are generally unheard of in the groups studied — the Hadza in Tanzania, the San in Namibia, and the Tsimane in Bolivia. Meanwhile, the Canadian media fusses and frets about the its nation’s sleep deficit, insisting that 60% of Canadian adults feel tired most of the time, on an average of 6.9 hours of sleep per night, with 30% of people sleeping less than six hours. Why do people living in contemporary society seem to need so much more sleep than hunter-gatherers?

Cold enough for you?

The answer may have to do not with time but with temperature. While we imagine that people who live without electricity go to sleep as soon as the sun sinks below the horizon, in reality these groups wait for the temperature to drop at night and don’t retire until about three hours after sunset, and get up in the morning at the coolest time of day, right before sunrise. This temperature cycle is mimicked by our own bodies during sleep, when our core temperatures cool. So while light plays a significant role in regulating our circadian rhythms, and has been the focus of sleep specialists who recommend darkening rooms for sleep and exposure to blue light in the day, the newest research suggests temperature may be even more significant. Following the environment’s temperature rhythm more closely and naturally could be a key to improving sleep for people in cities. Sleep specialists are now advising that the optimum temperature for sleep is 19C and recommend breathable bedclothes that can be easily removed. Sticking arms and legs out from under the covers is also an acceptable cooling technique, they say. And that old chestnut your grandma taught you about taking a hot bath before bed? Counter-intuitively, it’s the cooling you experience when you get out of the hot water, helps you sleep better.

Temperature as a treatment for sleep has been taken a step further by a US company that says it has a cure for insomnia. Sleep specialist and founder of the Cereve Sleep System, Eric Nofzinger, suggests that insomniacs have too much metabolic activity in the frontal cortex — activity which can be slowed by gently cooling the region. The product he’s developed consists of a soft plastic cap that you wear in bed at night that’s connected to a software-controlled bedside device that continuously pumps fluid into a pad on your forehead and so cools the brain. The process is called frontal cerebral thermal transfer and the device has been tested and approved by the FDA with a proposed release date some time in the latter half of this year. In randomized controlled studies, the cooling caps were found to both reduce brain metabolism during sleep, especially in the frontal cortex, and also to reduce the wearer’s core temperature, further deepening sleep. The cooler the setting, the more effective the device is at allowing those with insomnia to sleep like normal sleepers..

Before recommending possible remedies to your sleep-concerned patients it’s best for them — and for you — to first figure out how much sleep you need to feel rested. And there’s a simple way to do that. Go camping for a few days, ideally in winter or on cool spring or fall nights. Multiple studies have shown that even a single weekend spent in cool weather — without the use of electric light or devices after sundown — can be enough to significantly recalibrate circadian rhythms and help you sleep longer and more deeply.

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