We live in the age of the quantified self. Knowledge is power, and that applies to the body too. There are gadgets to measure pretty much everything we do: how much we move, how we move, what we eat, how we sleep… You name it, there’s an app for it. Problem is, many of these gadgets don’t do what they claim.
This thing can help you, yes you, become like Nikola Tesla. (Photo: NeuroOn)
Jordan Gaines has already written about the flawed sleep apps for your phone. The major problem with these apps is that they don’t actually measure sleep. The most reliable way of detecting sleep and its different stages is by polysomnography: a combination of EEG (brain activity), EMG (muscle activity) and EOG (eye movements). A phone that’s lying next to your pillow simply cannot do that.
The team running the NeuroOn kickstarter recognizes this flaw in other sleep apps and adds a mask that adds EEG, EMG and EOG to a sleep app. But, where most apps and gadgets aim to give you longer and more solid sleep, this project is specifically aimed at letting you get by with next to no sleep at all. You get more time to relax, have fun and take over the world without having to stop to do something as stupid as sleeping. According to them you too can be superman while only sleeping 2 hours per day when you buy the NeuroOn sleep mask. After all, Great Men of History like Nikola Tesla, Leonardo Da Vinci, Winston Churchill and Thomas Edison did it and they were pretty super.
Think this sounds a bit too good to be true? You’re completely right. Long story short, this kickstarter project is complete and utter nonsense, with an absurd premise and fatally flawed execution. Here’s why:
Inside of the NeuroOn sleep mask, showing the placement of the sensors. (Photo: NeuroOn)
So what is this NeuroOn sleep mask anyway?
The NeuroOn sleep mask looks a bit like a hybrid between a sleep mask and a ski mask. Inside it there are 3 sensors for recording brain, eye and heart activity, some amplifiers and circuitry that can send the signals to your phone via Bluetooth, and some other stuff. The kickstarter page sadly doesn’t provide much technical information: there are buzzwords instead of technical specifications. The NeuroOn will also have an app that can presumably analyze the recorded activity and tell you how you slept, as well as how you could do better, specifically less, in the future.
The NeuroOn seems to be designed as a kind of wearable alarm clock that wakes you up at exactly the right time of your sleep cycle, leaving you refreshed and awake after a short nap.
I don’t want to waste all this time sleeping!
Too bad, get over it.
There is no single magic number of sleep hours everyone should get, but the vast majority of people need between 7 and 9 hours of sleep per day. There are short sleepers that can get by on 5 or 6 hours per night without needing an alarm clock to get up in the morning, but these people are pretty rare. Healthy people who need even less sleep are almost nonexistent. Extremely short sleep duration is often a sign of psychological or somatic illness and is linked to increased mortality. Each of us builds up sleep need (or sleep pressure) at a differently during the day. The only way to compensate that sleep need is by sleeping and getting the required amount of slow waves. This can be done in a single sleep period, or in several, as long as the required amount of deep sleep happens.
The kind of long term sleep restriction the NeuroOn intends to achieve (they advertise total sleep times of 6 to 2 hours) cause a host of unhealthy and unpleasant side effects: it not only makes you more susceptible to cardiovascular disease, obesity and depression, to name a few. A recent paper suggests that some of these effect already appear when sleep duration is shortened by only a few hours, from 8 hours per night to 6 hours. It’s important to note that while the subjects in this paper didn’t feel like they were doing worse, they objectively were.
Someone who tries to sleep too little will also inevitably start falling asleep during the day. This can lead to pretty dangerous situations, for example when driving. Moreover, sleep deprived people have reduced reaction times, are less creative and are worse at estimating risks and outcome of their decisions.
Simply put, humans cannot survive on only a few hours of sleep per night. Extreme sleep restriction is not only a very bad idea, but also pretty much impossible to do for a longer period. Coffee and loud music only help counter sleep pressure for so long, you will start to fall asleep eventually.
Could this polyphasic sleep thing work?
But, you might argue, the NeuroOn doesn’t just limit my sleep time to a single bout, it gives me tactically placed powernaps throughout the day. These naps will keep me awake during the day, just like multiple spaced out meals will keep me from feeling hungry. If these meals are too small, however, you will still feel hungry all the time. In the same way, if the total amount of sleep from these naps is less than the amount of sleep you need, you will feel sleepy no matter how well the naps are spaced over the day. Sleep during naps isn’t magically different from regular sleep periods, it’s just shorter and less deep. As I wrote before, sleep need builds up during the day and gets dissipated during sleep. A short nap can dissipate a little of your sleep pressure, but longer sleep periods are much more efficient because there is just not much time to get a good amount of deep sleep in 30 minutes or so.
O, and I want to take over the world too
But even if the naps are long enough to satisfy your total sleep need, could a polyphasic sleep pattern still work?
Polyphasic sleep is, contrary to what the NeuroOn team claims, a sleep pattern where 50% or less of total sleep occurs within a single sleep period. It is not a magic sleep pattern that can turn you into the next Napoleon Bonaparte. Many animals display polyphasic sleep, but humans seem to be an exception.
Adult humans do not display polyphasic sleep behavior. Babies do: they sleep on and off during day and night and only develop a clear day-night rhythm as they get older. Young children do have a clear day-night rhythm, but they still need one or more a naps and a long night of sleep. The closest most adults get to a polyphasic pattern is a main sleep period at night with an additional nap in the afternoon (which is technically not polyphasic). Given the societal pressure to not sleep, it could be that we are simply conditioned to abandon the ‘natural’ inborn polyphasic pattern as we age. Sleep patterns of people in timeless environments*, suggest that this is not the case: their sleep is still largely confined to a single long bout every 24 hours in the absence of any zeitgebers, although there tend to be multiple naps in addition to the main sleep period.
Parents are essentially forced to return to the early life polyphasic sleep behavior after they have a baby. Mothers, and to a lesser extent fathers, synchronize their sleeping patterns to those of the child. While parents obviously survive this enforced new pattern and end up getting used to it, their functioning is suboptimal. In other cases where the world interferes with the need to sleep, such as during long distance sailing races like the OSTAR, people adopt polyphasic sleep patterns as well. Two-third of the questioned sailors that reported sleeping relatively little (~6 hours) in multiple short (20-30 minute) naps finished the 10-day race faster than those who slept more or used longer sleeping periods. Interestingly, although the sailors say they try to train themselves on the napping pattern before the race, only a minority (10%) is able to do so.
So, humans are clearly capable of adopting a polyphasic sleep behavior when they really need to, but that doesn’t mean it’s necessarily a good idea. Is there evidence for benefits of polyphasic sleep in humans?
Research on polyphasic sleep patterns is mostly related to improving alertness and performance during shift work or during jobs that require continuous work. In general, these polyphasic sleeping patterns are used as a means to avoid sleep deprivation: humans need to sleep, whether the job agrees or not.
One paper by Porcu and colleagues reports no ill effects of a polyphasic sleep pattern (2 hours on, 4 off) when it was alternated with an entirely off-duty days in 9 adult men. Even though they slept less than usual, the men were able to stay awake during the wake periods without any trouble. The wake periods were quite short (they comprised a regular 8-hour working day split in 4), meaning that the subjects were left with 16 hours for sleeping ( although they didn’t sleep during the first off-period of the day). Even with ample time to rest, the subjects slept much less than they usually would. A major limitation of this study is that performance during the wake periods wasn’t assessed. Importantly, the subjects were allowed a full day of rest after each polyphasic day, allowing them to make up for any lost sleep.
Another real life application of polyphasic sleep patterns occurs in professions that require constant rotations of less than 12 hours. A pattern of 6 hours on, 6 off isn’t unusual for ship’s crewmen and it theoretically leaves plenty of time for sleep during the two off-periods. Even though the crewmen get enough time to sleep (12 hours in total), their sleep quality and daytime sleepiness is much worse than with a single sleep period.Their performance is also worse than with a normal, monophasic sleep pattern. A more recent paper shows similar results with recorded sleep, reaction times and subjective sleepiness in crewmen during a 4 hours on, 8 hours off watch system. Strikingly, one third of all participants slept during at least one of the watches. This paper also shows that sleepiness and sleep still peak during the night and early morning watches, even after an 8-hour sleep opportunity, which is also the time of day when most accidents occur. This shows that while polyphasic sleep patterns may be practical under certain circumstances and are definitely preferable to complete sleep deprivation, they are not very well suited for long-term use.
Very cute method for achieving less sleep in shorter naps
In his book Why we nap, Claudio Stampi argues that polyphasic sleep with ultra short sleep cycles may actually be feasible and beneficial if people are allowed to slowly get used to such unusual patterns. Sadly, I have no access to most of the original papers discussed in this book.
He discusses two major groups of polyphasic sleep patterns: anchor sleep patterns (a 4-hour sleep period followed by several naps) and ultra short polyphasic patterns (consisting only of a number of short naps). Although the most extreme anchor sleep patterns (4 hours + 6 20 minute naps) did not allow for deep sleep during the naps, performance is not worse than in less extreme patterns with fewer, longer naps. However, performance in all polyphasic groups was worse than before the napping protocol (95-45% of baseline performance). As an example of the ultra short polyphasic patterns, Stampi studied the legendary sleeping pattern of Leonardo Da Vinci**: a 15- or 30-minute nap every 4 hours, giving a total sleep time of less than 3 hours per day. For this, he took one healthy volunteer who was put this napping regimen for 19 or 48 days. The subject apparently adapted well to the protocol, both subjectively and objectively, but no data is shown. It is worth noting that Stampi doesn’t consider the performance of the subjects in the anchor-sleep study mentioned above much worse than normal either, so without viewing the data it’s impossible for me to say anything about that. Still, it seems to indicate that at least some individuals are capable of adapting to polyphasic patterns with an extremely short sleep period.
A major limitation of the studies reported by Stampi, however, is that the wake EEG during the sleep restriction period is not assessed. This means that it is possible for the subject to have a large number of microsleeps (sleep episodes of less than 10 seconds) during the time he is supposed to be awake. While these microsleep episodes are by themselves not very efficient at reducing sleep pressure, many of them together have a significant effect on sleep homeostasis: short periods with slow waves are better than none at all. Moreover, during periods with very high sleep pressure, sleep pressure may be compensated during states other than NREM sleep. Even if standard scoring and analysis methods for human sleep stages are insufficient to detect such short intrusions of sleep into wakefulness. Additionally, even if the subject tries very hard, he may not even have noticed that he has briefly fallen asleep: many people are not very good at estimating when they are about to fall asleep and only indicate feeling sleepy after they’ve already had a number of microsleeps.
Polyphasic sleep patterns are sometimes used in the lab to study the effects of circadian (time of day) effects on sleep regulation: many short naps are alternated with short wake periods with a small meal and no other activity that may change sleep need independent of time of day. Importantly, the total amount of time subjects are allowed to sleep is typically not reduced in these studies. Such constant routine protocols have revealed a single wake maintenance zone in the late afternoon, during which it is very difficult to fall asleep. If humans were truly polyphasic, we would likely not have a single pronounced wake-maintenance zone. A polyphasic animal might have multiple wake maintenance zones, or none at all.
In conclusion, humans do not seem to benefit much benefit from a polyphasic sleep pattern over a monophasic one, even if it allows for a sufficient amount of sleep. As boring as it sounds, our sleep is most effective at night, in a nice long bout.
An EEG cap is the easiest way to attach many EEG electrodes to the head. The electrodes near the eyes are recording EOG. Note that no EEG electrodes are placed near the eyes. (Photo: Tim Sheerman-Chase)
Can the NeuroOn measure your brain activity?
No, or perhaps very badly.
EEG, EMG and EOG are similar methods that are used to record activity of the brain, muscles and eyes, respectively. The NeuroOn has 3 electrodes (‘sensors’) for recording these signals that are placed on the forehead, between the eyes.*** This is problematic.
You can think of an EEG recording as trying to listen to people talking (brain activity) inside a room (the skull) by holding a microphone against the wall. The muscles and the eyes also give off electrical signals, like loud people standing close to your microphone. This means that your brain signal is much harder, if not impossible, to detect: it is buried under the much stronger activity from the muscles and eyes. This is why EEG electrodes are usually placed away from the eyes and any larger moving muscles.
One of the things that makes sleep EEG recordings a bit different from wake EEG recordings is that the subjects are, well, asleep (duh). This means that you cannot tell them to not move or not to touch the electrodes. Sleep EEG electrodes are usually stuck on using a thick sticky paste and some tape to make sure they don’t move around and mess up the recording. Just imagine how difficult it would be to hear something specific in that room when your microphone is moving around as well.
The NeuroOn mask is only held to the face with a single strap. So, when you move your head, or turn over in bed, or scratch you nose, the mask will move. It may not move much, but even a little movement of the electrode gives a huge mess in the signal. This pretty much means that a mask that will reliably record is also quite uncomfortable to wear: it has to sit on the face quite tightly so that the electrodes make a good contact with the skin and will not move. For the NeuroOn mask, this means that we are not only trying to listen to the people in another room with a microphone that moves around, but as soon as the electrode stops touching the skin we might as well be trying to listen from the other side of town. This means that even if the NeuroOn is able to detect EEG, the signal quality will be useless.
A typical polysomnography has a bunch of tape and covers to make sure the sleeper can’t mess up his recording. Those electrodes aren’t going anywhere. (Photo: Bre Pettis)
Can it measure when I sleep?
Even if the NeuroOn would able to get a decent quality signal (it won’t), I don’t think so.
This is mostly because the makers (even thought they claim to have some medical background) clearly have no idea how to detect sleep from the signals they try to record.
Sleep consists of two distinct states that alternate in sleep cycles throughout the night. These cycles are typically about 45 minutes long. Each state is identified by a combination of typical brain activity, muscle tension and eye movements. The first is slow wave sleep, or non-REM sleep (NREM sleep), which makes up most of our sleep time. Brain activity characteristic for this state has many slow waves, also called delta waves. These waves are a major indicator of sleep quality and depth. In human sleep this stage is subdivided into 4 substages, based on sleep depth. During a sleep cycle, NREM sleep gets progressively deeper and after some time in deep, restorative, NREM sleep, you will get an episode of REM (rapid eye movement) sleep. Brain activity in REM sleep looks similar to that during wakefulness, but muscle tension is very low and the eyes move rapidly from side to side, giving this state its name. The end of a REM episode marks the end of a sleep cycle, and the sleeper continues to sleep in shallow NREM sleep.
A gadget that wakes someone up based on EEG should wake them when they’re in shallow NREM sleep, at the end (or beginning) of a sleep cycle and not during REM sleep or deep NREM. Waking you up during those stages will leave you really groggy after waking up. So, it is useful for your app to be able to detect REM. When REM sleep ends at a certain time in the morning, the gadget should wake you. If you want the app to measure sleep quality as well, it needs to be able to properly detect sleep depth (slow waves), but it could also detect if you get nice long NREM episodes.
The NeuroOn does none of these things: based on the limited information on the kickstarter page, it focuses on eye movements, muscle tension or heart beat (the top part of the page talks about EMG, while later on they show ECG traces) and the faster activity in the EEG. This combination is pretty much useless for detecting sleep states: it would even be hard to reliably detect wakefulness with this combination. I am not sure why they chose the faster activities, but I suspect it has to do with movement artifacts and electrode location: the kind of signal changes caused by moving electrodes can look very similar to the real slow waves in the EEG. Detecting slow waves from a terrible quality signal is pretty much impossible. It might also just be cluelessness on the part of the makers though. Even though the team claim to work with sleep centers to improve their sleep detection, no sleep researchers are listed.
As a sleep researcher, it really makes me kind of sad when that my favorite physiological process gets such a shoddy treatment. Just because everyone sleeps, that doesn’t mean that sleep is trivial or optional (or easy to detect and analyze, for that matter).
Finally, I find it both confusing and sad that the product is marketed with ‘regain control over your time’. I don’t even know what that means, but it fall in the same confusing and sad category as liquid food as fuel. Apparently some people seek to remove themselves from their physiology, and apparently from the pleasure a good night’s sleep can bring. It just seems like setting yourself up for failure.
Many people have pre-ordered a thing that has no basis in science at all, but hey, who needs data when the makers claim Bruce Wayne would have used one (what with his love for gadgets and all the time spent batmanning and all).
* These environments do have time, of course. A timeless environment in a sleep lab is an environment without external cues about the time of the day: light and temperature are kept constant, meals are evenly spaced over the day and there are no clocks to give the inhabitants clues about the passage of time outside the lab.
**Although the Da Vinci papers were published by Claudio Stampi in 1991 and 1990, I cannot find them on pubmed or in individual form anywhere online. If any of you find a copy, I’d love to see it and take a closer look at the data.
*** On the pictures, it looks like there are 3 electrodes. I don’t know if this means they record 3 channels of the same signal, or if they have a sensor each for their EEG, EOG and EMG signal. Neither option will solve the signal quality issues, though.
**** seriously, wtf
Sleep cycle app: precise or placebo?, by Jordan Gaines
Neurocrap funded by the masses: NeuroOn and No More Woof
Better sleep infographic by the National Sleep Foundation
Principles and practice of sleep medicine, Roth and Dement , 5th edition, Elsevier. (read chapter 2 here, about normal sleep)
Immune, inflammatory and cardiovascular consequences of sleep restriction and recovery, B Faraut, KZ Boudjeltia, L Vanhammed, M Kerkhofs, Sleep Medicine Reviews, 2012
The cognitive cost of sleep lost, J McCoy and R Strecker, Neurobiol. of Learning and Memory, 2011
Sleep and alertness during alternating monophasic and polyphasic rest-activity cycles; S Porcu, M Casagrande, M Ferrara and A Bellatreccia; Int J Neurosci, 1998
Getting through to circadian oscillators: why use constant routines; JM Duffy and D-J Dijk; Journal of Biological Rhythms, 2002
Why we nap: evolution, chronobiology and functions of polyphasic sleep; Claudio Stampi, Birkhäuser, 1992
The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation; HPA Van Dongen, G Maislin, JM Mullington, DF Dinges, Sleep, 2003
Trends in the prevalence of short sleepers in the USA: 1975-2006.; KL Knutson, E Van Cauter, PJ Rathouz, T DeLeire, DS Lauderdale; Sleep, 2010
The prevalence of short sleep duration by industry and occupation in the national health interview survey; SE Luckhaupt, T SangWoo, GM Calvert; Sleep, 2010
Sleep duration and mortality: a systematic review and meta-analysis; L Gallicchio and B Kalesa;, Journal of Sleep Research, 2009
Timing of REM and stages 3 + 4 sleep during temporal isolation in man; ED Weitzman, CA Czeisler, JC Zimmerman et al.; Sleep, 1980
Sleepiness and sleep in a simulated “six hours on/six hours off” sea watch system; CA Eriksen, M Gillberg and P Vestergren; Chronobiology International, 2006
Chronic sleep curtailment impairs the flexible implementation of task goals in new parents; F Plessow, A Kiesel, A Petzold, C Kirschbaum; Journal of Sleep Research, 2011
Infant and mother sleep patterns during 4th postpartum week; SI Quillin SI; Issues Compr Pediatr Nurs. 1997
The sleep patterns of normal children; KL Armstrong, RA Quinn, MR Dadds; Med J Aust, 1994
Sleepiness is not always perceived before falling asleep in healthy, sleep-deprived subjects; US Herrmann, CW Hess, AG Guggisberg, C Roth, M Gugger and J Mathis; Sleep Medicine 2010
Those Stampi papers I can’t find
Forty-Eight days on the “Leonardo da Vinci” strategy for sleep reduction: Performance behaviour with three hours of polyphasic sleep per day, Stampi C and Davis B, Sleep Research 2:471, 1991
Leonardo da Vinci’s polyphasic ultrashort sleep: A strategy for sleep reduction? I. Sleep architecture, Stampi C, Moffitt A and Hoffman R, Sleep Res 19:408, 1990
Three weeks with 3-hr monophasic sleep per day: A control study to the Leonardo da Vinci schedule, Stampi C et al. (In preparation, but that was in 1992)
The NeuroOn pictures come from the NeuroOn kickstarter page.
The sleeping babies come from wikipedia
The EEG cap photo comes from Tim Sheerman-Chase’s Flickr page (under a creative commons license).
The polysomnography photo comes from Bre Pettis’ Flickr page (under a creative commons license).
Why? comes from Anna Vignet’s Flickr page (under a creative commons license)