The average human sleeps about eight hours a night for, on average, 75 years. That adds up to around two hundred and 22,000 hours in a lifetime. What if we could use this time to do something useful, like learning a language while sleeping? I’m sure this thought has crossed your mind as you lie in bed, scanning your appointments for the following day and wondering how you’ll ever fit everything in — if only you had a few more hours in the day!
If this is the case, you’re in good company. Luminaries from Benjamin Franklin to Jon Bon Jovi have poured scorn on the simple mammalian inactivity of sleep. Franklin famously asserted that, “there will be sleeping enough in the grave.” Bon Jovi concurred chorally: “Until I’m six feet under, / Baby I don’t need a bed, / Gonna live while I’m alive, / I’ll sleep when I’m dead.” Thomas Edison was not so spiteful of sleep itself, but looked down on those who overindulge: “The person who sleeps eight or ten hours a night is never fully asleep and never fully awake — they have only different degrees of doze through the twenty-four hours… We are always hearing people talk about ‘loss of sleep’ as a calamity. They better call it loss of time, vitality and opportunities.”
Nowadays, this loss of vitality has been repackaged as a loss of productivity. We’re told of the hyper-productive CEOs of the world’s richest companies who are awake and alert hours ahead of the rest of humanity. Tim Cook, the CEO of Apple, gets up at 3:45 every day, answers his emails and works out before heading to the office at 6:00.
Before we restructure our lives and set the alarm clock to shriek an hour or two earlier, we should take a step back. All the above is very normative: measuring success against CEOs is fairly futile (there can only be so many of them), and waking up at four in the morning to answer emails certainly isn’t everyone’s definition of success. What exactly is the relationship between sleep and success? Are the early birds flying high because they get up before the rest of us, or are they merely the victims of schedules tightening as they scale the career ladder?
Then there are the very real dangers of sleep deprivation, which has been linked to a host of afflictions ranging from a lower pain threshold to heart disease and diabetes. The pressures and paradigms of modern life have already taken their toll; Americans sleep over an hour less than sixty years ago, and approximately 36 percent are sleep-deprived — it’s a public health problem. Only 5 percent of us can get by on fewer than six hours sleep a night, which means you likely need more.
So where do we go from here? Modern lives are short on time and short on sleep, so what should we do to find the time for something as fulfilling and vital as learning a foreign language.
Is Learning A Language While Sleeping Possible?
Hypnopaedic learning, or sleep-learning, is the acquisition of information while asleep. It’s difficult to imagine reconciling the activity of learning with the inactivity of sleep, but that hasn’t stopped a few scientists and many cunning marketeers from trying. The idea of switching on a tape player and closing your eyes to wake up fluent sounds as appealing as it does preposterous.
That said, perhaps we shouldn’t be so quick to dismiss the power of the unconscious: There are numerous reports of people awaking from comas with sudden and surprising expertise in a language they hitherto couldn’t speak; a 22-year-old Australian who spent a week in a coma and awoke fluent in Mandarin, or a promising young English footballer who awoke speaking fluent French and believing he was Matthew McConaughey, or a Croatian girl that awoke suddenly able to speak German.
But what evidence exists for hypnopaedic learning? Not a lot, unfortunately. As Jennifer Ackerman notes in her splendid 2007 book Sex Sleep Eat Drink Dream, learning a language while sleeping “is probably impossible, [and] attempts to teach slumbering adult subjects vocabulary of foreign languages or lists of items have failed miserably.”
More recent studies have pointed to at least some advantages of revisiting previously learned information in your sleep, however. In 2012, researchers from Northwestern University taught participants two simple songs, one of which was then played back to the test subjects during a period of deep, slow-wave sleep. The test subjects consistently recalled the song they had heard while asleep more vividly than the other tune.
In 2014, similar results were obtained in a study into the recall of recently learned vocabulary. Re-exposure to words during non-REM sleep improved memory of these words, and the researchers also recognized the same patterns of theta wave oscillations normally associated with successful memory encoding while awake.
This is pretty interesting, but it’s still a long way away from the dream of the turbo-charged, unconscious process of learning a language while sleeping. Indeed, as Florence Cardinal of Canada’s National Sleep Foundation said, “Disturbing sleep patterns in this way requires the brain to remain alert to listen, preventing you from attaining the sort of sleep which is actually so important for the mind.”
Unless you want to record lists of vocabulary to play back to yourself every night, it sounds as if we should retreat to our waking hours to learn a language.
Does Sleeping Help At All?
The fact that you can’t really sleep and learn at the same time doesn’t mean sleep isn’t important for learning, however. Research shows that while you’re asleep, your brain is hard at work — processing information you took in during the day. Many people are familiar with the REM phase of sleep, which is when most dreaming occurs, but a lesser-known phase is slow-wave sleep, or SWS. Researchers have found SWS to be an important phase for memory processing.
Dr. Jakke Tamminen, a psychology lecturer and researcher at Royal Holloway University of London, studies how sleep affects learning and the role memory consolidation plays in that process.
One of Tamminen’s studies involved two groups: a control group of participants learning new vocabulary words and then being tested on them later the same day (with no sleep involved) and an experimental group that was tested after sleeping. But these weren’t just random vocab words. They were words from a fictional language with a hidden rule binding them together. The study found that participants in the experimental group were able to understand and apply the rule while sleeping and were better able to recall the words they learned than those who did not sleep.
Memory consolidation is linked to what are called sleep spindles, or short bursts of brain activity that occur during the SWS phase of sleep and are involved in the reactivation of new information. The study found that participants who exhibited the highest number of sleep spindles showed the most signs of integration between existing memories and new ones, which helped them retain the new vocabulary.
“Teachers have long suspected that proper rest is critical for successful learning. Our research provides some experimental support for this notion,” said Dr. Kathy Rastle, head of Royal Holloway’s psychology department.
So while some CEOs are adamantly anti-sleep, trying to optimize every hour of your day might not be the best approach. While you could technically put on an eight-hour YouTube video of Spanish vocab before you sleep, you might end up disappointed by how little you recall. Instead, study and then get some rest. Your body needs it.
This article was originally published on May 25, 2016. It has been updated with more recent research.