Do you feel like the usual “8 solid hours” approach to sleeping just isn’t working for you? Are you waking up frequently in the night? Feeling tired earlier in the day than most people?
If so, perhaps you’ve considered alternative methods, like trying to get the same amount of daily sleep time though multiple periods of napping?
This sleep strategy has become a common choice with many touted benefits. However, there are new research findings which suggest that some versions of the approach can actually cause harm.
In this article I’ll examine the problem more closely so that you can make an informed decision without taking on any unexpected risks.
What are alternative periodic sleep patterns?
Humans are usually expected to stick to a monophasic sleep cycle, meaning that we get all of our sleep in a single session each day/night. Many people take it for granted that this is the pattern they are “supposed to” sleep in, but it may in fact be more of a social requirement than biological.
Alternative schedules that utilize multiple shorter periods of sleep have been gaining in popularity over recent years. This may be in response to steadily increasing workloads and schedule disruptions that have been heaped upon students and workers alike.
A major complication of discussing alternative sleeping patterns is their naming. In much of the available literature, all forms of non-monophasic sleep are grouped together and called by a needlessly large number of names (structured sleep, interrupted sleep, intermittent short sleep, etc.).
Other than causing confusion, inconsistent naming is a problem because important details emerge when we study alternative periodic sleep patterns as two distinct groups:
- When the pattern is composed of exactly two periods of sleep in a day, it’s called biphasic.
- Sleep patterns with more than two separate sleeping sessions in 24 hours are referred to as being polyphasic.
For simplicity’s sake, we’ll stick to referring to alternative sleep patterns by the above definitions.
What do we know about biphasic sleep?
It’s been suggested that we have a natural tendency to sleep in biphasic patterns. The supporting evidence is becoming pretty convincing.
- Research has shown that modern humans slip into a biphasic sleeping pattern when exposure to artificial light is removed.
- Historians have shown that before the industrial revolution, it was common to get up in the night and then sleep again later.
- In one study, biphasic sleeping resulted in the best exam results for medical students, while polyphasic was the worst, though only slightly more so than regular monophasic sleep.
- Research suggests that babies have a biphasic sleep pattern until early childhood.
What’s known about polyphasic sleep?
In stark contrast to biphasic schedules, polyphasic sleeping appears to be associated with less desirable observations. However, there aren’t a lot of studies that include and separate the two at this point in time:
- As noted above, polyphasic schedules resulted in the lowest exam scores in a comparison of sleeping patterns among medical students.
- Research shows that polyphasic patterns are common among elderly people, who also experience a decline in the psychological benefits of sleep.
Worrying new research findings
A 2016 study identified significant neurological changes as potential side-effects of polyphasic sleep patterns. After switching to a polyphasic pattern, neurons in parts of the brain associated with sleep-wake activity decreased in numbers; furthermore, the remaining ones were functionally impaired.
Disruptions in the sleep-wake cycle are bad news in most cases. They are connected to symptoms similar to those found in sleep deprived individuals, like memory impairment and confusion.
Despite the seriousness of cycle disruptions, it goes without saying that disappearing brain matter is probably the most disturbing finding in this study.
Although this research is new, it implies that we need to re-examine polyphasic sleep patterns as a viable alternative sleeping strategy.
Why would polyphasic sleep be harmful?
Put simply, polyphasic sleep may reduce our time in deep sleep. Normally, our sleep cycle runs from stages 1 to 4 and then enters the rapid eye movement (REM) stage. The cycle repeats every 90-110 minutes, getting shorter each time.
Deep sleep, also called slow-wave sleep (based on lower brainwave frequencies), is comprised of the third and fourth stages of the sleep cycle. And it’s thought that during deep sleep, several important processes take place:
- Memory consolidation.
- Cellular recovery from the energy demands of waking mental activities.
- Changes in connections between cells (aka neuroplasticity).
If polyphasic sleeping does corrupt the sleep cycle progression, it may prevent these activities from being efficiently performed. This could then result in the problems I mentioned earlier.
Despite the importance of the entire sleep cycle, the brain is programmed to go into REM at all costs, even at the expense of other stages. So if you don’t get enough REM sleep, you’ll pass through the other stages more quickly. This is called REM rebound.
It’s possible that polyphasic schedules make the brain respond as if REM time is threatened. This could force us into the REM stage earlier, reducing the amount of time spent in other stages.
What’s the bottom line?
While it can’t be said that there’s definitive evidence one way or the other, it certainly appears that polyphasic sleep patterns have the potential to cause problems.
Perhaps if you’re thinking of trying this style of sleeping, it might be better to wait until more research is done. And if you’re already sleeping like this, it might be a good idea to monitor yourself for any kind of memory or performance problems.
Biphasic sleep, on the other hand, seems to hold up as a worthy and perhaps superior alternative to the traditional single session variety. Still, messing with sleep cycles is risky business and should be treated with caution.
Unfortunately, many people have social engagements that make it difficult to test out alternative sleep patterns. In which case it may be safest to stick to the traditional monophasic pattern to avoid causing significant amounts of stress in other areas of life.