What do sleep and a symphonic work have in common?
No, this isn’t the set-up to a bad joke. In terms of structure and function, both are strikingly similar.
- Both are comprised of several distinct movements
- Both need a whole group of different instruments
- Each utilizes a conductor
- There are different and distinct parts for each and every organ to play throughout
A little night music
In order to play a symphony, you need an orchestra comprised of different instruments, with a different part of music for each type of instrument.
In order to sleep, your internal organs each need to do different things like secrete melatonin, dial down the digestive system, and slow down breathing. On top of that, you need different organs to secrete growth hormones to repair body tissues. You need different neurons to process information and consolidate the important parts into long-term memories during each sleep stage.
But they don’t just do this willy-nilly. Just like in a symphony, there’s a certain rhyme and reason as to why things happen when they do over the course of a night.
The composition of sleep
To correctly play a symphony as written, each instrument needs to play the correct movement at the right time; if Beethoven’s 5th didn’t start off with its signature “Dah-Dah-Dah-Dahhhn”, the audience would know something was wrong. Similarly, sleep has a distinct type of architecture.
A typical night of sleep is front-loaded with deep sleep earlier in the night (the first movement) while saving the REM for the second and third parts of the night. Light sleep shows up throughout, like an overarching theme, while periods of wake are the natural breaks and pauses within each piece.
However, if lots of REM showed up ahead of Deep, or if you just had huge chunks of Wake, then your body would know that something was out of sync, and it would scramble to correct it over the next few nights.
To help keep it all together, there needs to be some overarching direction and guidance. An orchestra has a conductor with a master score while we have the suprachiasmatic nucleus in our brain’s pineal gland. But even the best conductor can’t be individually conducting each instrumental group–much less each musician.
To compensate, the music score has time indicators as to when each part does their thing. Likewise, our internal organs and cells appear to have their own circadian rhythms that move at different times based on different cues.
Many parts to play
In an orchestra, you can have a violin section divided into three parts, with all of them playing at once or with each group playing at different times. Our own brain divides itself into sections that fire at different times and frequencies during the night, depending upon the sleep stage and other bodily factors. A good example of this happens when we fall asleep and when we wake up. Certain regions of the brain fall asleep before others, making it tricky for trained sleep technicians to sometimes determine when one is asleep or awake.
Of course, the more different parts that a single group is playing at once, the harder it becomes to figure out what each individual line sounds like. Sometimes the first and second violins are playing so frantically that one can’t hear the third–or even notice that the third violins aren’t playing at all. Brain signals work in much the same way, with noisier, higher frequencies sometimes drowning out or suppressing lower ones.
How best to record?
With the potential to miss out on key information, where to put the microphone to get the best recording is always a challenge.
The S+ works by detecting the movement of your upper body while you sleep. The movement it detects consists of the expansion and relaxation of your chest as you breathe in and out, and overall body movements such as positional changes, arm twitches and shrugs. The S+ includes software algorithms that recognise the combination of respiration and body-movement signals, so that the overall sleep state can be reliably assessed.