The sleep machine

By Marcus Wilson 06/05/2013

I came across this paper while doing a bit of reading about the applications of transcranial magnetic stimulation (TMS). A TMS machine applies pulses of magnetic field to the brain. The rapidly-varying magnetic field induces an electric field (Faraday’s law) and this in turn influences neural activity (but just how and where is an open question).  A team of leading sleep researchers (Marcello Massimin, Guilio Tononi and Reto Huber)  has probed the state of the brain using TMS for various states of consciousness. What they found was very interesting. When in deep sleep, a pulse from the TMS machine generates a single slow wave of activity, which has the same form as the naturally occuring slow waves that are a hallmark of deep sleep.

Now, these slow waves are important – they have been linked with memory consolidation. The more slow waves you have when sleeping, the better you are committing things into memory. And artificially-generated slow waves do the job too. 

In other words, the TMS can be viewed as generating artificially enhanced sleep and therefore artificially improved memory. 

But wait, there’s more (as they say). When someone is awake, a TMS pulse doesn’t do anything. But for someone teetering on the edge of sleep, but still not quite in it, a pulse from the machine can be enough to send them over the edge. So here we have a way of pushing someone into sleep more quickly than they’d otherwise get there. A cure for insomnia? Perhaps not – I mean, TMS machines are hardly unobtrusive, but interesting nonetheless. The remaining question is, do we get one for us or the baby?