Before the development of brain wave sensors, scientists barely knew what the brain does when it sleeps. To this day, sleep is an evolutionary and physiological conundrum, although a clear relationship is now recognised between lack of rest and the onset of disease, as well as reduced life expectancy. Today, neurotechnology startups are attempting to take the relationship between sleep and tech to the next level, using bidirectional interfaces that not only read the brain, but also try to manipulate it while it rests.
For decades, scientists assumed that the human brain switches off to preserve energy when it isn’t awake, like a household appliance on standby. Neurotechnology proved them wrong. During the 50s, researcher Eugene Aserinsky rigged his own son, aged eight, to an old brainwave sensor while he slept. The curvy lines traced by the device’s pens on the graph paper showed a pattern of neuronal activity consistent with that of a fully active brain. That was how Aserinsky discovered REM (rapid eye movement) sleep, a phase during which we dream while the mind orders thoughts and consolidates memory.
The biological reason for sleep is still unknown. In 2010, Aserinsky’s fellow sleep researcher, William Dement, who had already retired, joked: “As far as I know, the only reason we need to sleep that is really, really solid is because we get sleepy.” However, what we do know about the process, we know thanks to neurotechnology. Use of electroencephalography (EEG) first, and then modern neuroimaging techniques like positron emission tomography and functional magnetic resonance imaging, have revealed how the brain behaves while we sleep, which is an important clue for why we sleep at all.
Hence, we know that sleeping neurons emit brain waves of certain frequencies, which can be classified into four phases of rest, repeated in cycles every night. Studies of sleep deprivation and studies that follow people who suffer insomnia and brain lesions have provided insights into the crucial physiological processes which the body undergoes during each phase, such as muscle repair, hormone release, immune system activation or the reinforcement of neural pathways.
During the 1970s, this body of scientific knowledge was big enough to consolidate a new discipline, sleep medicine, which nowadays makes use of neurotechnological techniques such as polysomnography to diagnose sleep disorders. The number of people who sleep too little or too poorly is growing, according to global figures; this is a public health problem. Extreme sleep deprivation, of the sort suffered by patients with a rare genetic disease known as fatal insomnia, causes a certain and early death.
Wearable technology to improve sleep
In order to improve sleep quality and quantity, technologists have moved on from creating brain-machine interfaces to monitor the sleeping brain—they now design devices to directly control sleepiness. The more sophisticated gadgets are flat headbands wrapped in cloth, which contain electrodes to measure brain waves and sensors for movement, heart rate and breathing. They are also equipped with microphones that project acoustic waves directly into the skull, to infuse the brain with sounds of a certain frequency at night.
The idea is based on experiments which have validated the efficacy of sound waves to modulate the deepest phase of rest, known as slow wave sleep. A study published in the journal Neuron in 2013 found that sound waves which are in phase with brian waves of this sleep stage induce “auditory closed-loop stimulation” of the brain. This enhances neuronal oscillation of the slow wave phase and its associated benefits, such as memory consolidation. The study was a small one (only 11 participants), but it hinted at the potential of the neurotechnological market which now adopts these methods.
The Dreem device, for instance, designed by a French company of the same name, emits a frequency of sound known as pink noise whenever it detects that the user has entered slow wave sleep. According to the manufacturers, this technique lengthens the deep slumber and improves overall sleep quality. However, a large part of the company’s scientific literature on their technology is not public, and the headband, which is already on sale for 399€ ($499), has not been subjected to a peer-reviewed clinical trial.
Its main competitor, Philips’ SmartSleep device ($400), works in a similar fashion and is backed by a few scientific studies in the public domain, like one published by the journal Sleep during november 2019 which confirms some cognitive improvement in several men who slept with the headband. This wearable is marketed towards people who can’t or don’t want to sleep for more than six or seven hours each day, due to their lifestyle. The manufacturers hold that 70% of such users claim to feel more rested on mornings after they have used the headband but, again, there is a dearth of independent verification for such claims, and there are no studies following large cohorts of users for significant periods of time.
The future of assisted sleep
As of yet, neurotech for sleep is expensive and uncomfortable. Its promises and benefits are modest. However, these EEG headbands are the best sleep monitors you can find outside of a scientific laboratory, and we can expect great improvements to their design in coming years, given they are pioneering products. They are not medical devices, but if their manufacture and distribution become regulated as such, these wearables may allow diagnosis of sleep disorders from patients’ homes, with all the benefits and challenges that would entail.
To improve sleep, there is another class of neurotechnological devices, which aim to manipulate the brain using electrical currents. The American company Thync develops gadgets that do just this, using an adhesive pad on the back of the neck. The “pods”, as the company calls them, stimulate nerves which allegedly induce calm and reduce the brain’s stress and anxiety responses. However, one user who has tested the latest trial version claims the experience is similar to a neck massage.
This product is the successor of another device which Thync launched in 2015 and which has now been removed from the market: the old version produced light electrical pulses on the neck and temples of the user to energize or relax the mind, according to the chosen function. The method is akin to a watered-down electroconvulsive therapy, but it lacks medical regulation. It is validated, however, by at least one study, published in 2015 in Scientific Reports, which found positive effects on users who had received that sort of direct electrical stimulation.
The original product was widely criticized; users claimed to feel uncomfortable, especially under the effects of the energizing setting, or to not feel anything at all. Those who did appreciate the device’s effects compared the relaxing input to smoking cannabis, meditating or taking a calming drug. It remains to be seen whether the new version of the wearable has improved the experience, but one thing is clear: sleep-controlling neurotech has a long way to go. Drastic improvements can be expected of the field in coming years—for now, attempting to activate neuronal switches with acoustic or electrical stimulation of the skull is akin to attempting surgery with a machete.