Rock-a-bye adults

Perceptual psychologist Helen Keyes from Anglia Ruskin University has stumbled upon a slumbering story on sleep, and she spoke to Katie Haylor...

Helen - This paper was looking at the best way to get a good night's sleep. And specifically, the best type of sleep environment and whether sleep can improve our memory performance also.

Katie – Right then. So, what did they do and what did they find?

Helen - Well contrary to what we might naturally assume that a quiet environment with a lack of any sort of stimulation might be the best way to get a good night's sleep. These authors thought that maybe a rhythmic rocking motion might induce a deeper sleep and they hypothesized that this might be because rocking can tune in to the particular neural patterns that are happening when you're going to sleep and perhaps regulate those.

Katie - So we rock babies stereotypically to sleep. Is this suggesting that we potentially should be rocking ourselves as adult, is not too farfetched really.

Helen - I love that idea. So, we do rock babies and I think it's really nice because it's something everybody naturally does when they have a child in their arms or a baby in their arms. And it suggests that it really might directly help people to go to sleep and enter that deep sleep more quickly.

Katie – Okay. So, let's dig into the science. How did they do this and what did they find out?

Katie - Okay. So, they took 18 healthy participants and there was quite a bigtime investment from participants here they had to sleep in the sleep lab for three nights in a row. So, the first night was just to get used to being in the lab environment and settling into sleeping there. The second two nights were experimental nights. So, on one of those nights you would be asleep on a bed with a motor beside you that could rock the bed. And that motor was on but not rocking the bed, so you could hear the noise of the motor, but it wasn't rocking you, that was a control. The second night you would be in the same bed but the motor this time would be attached to the bed and very gently rocking you in a consistent pattern all night. And those nights were alternated between participants, some had rocking first and then no rocking and vice versa. And while they were doing this people's neural activity was recorded while they were asleep. And participants also performed a memory task prior to falling asleep each night and when they woke up the next morning, which was a word pair association task. So we were able to see whether their memory was improved by the rocking.

Katie – Okay. This sounds like a very nice experiment to partake in. I personally would quite enjoy that I think. What did they find out?

Helen - So they found really interestingly by looking at your EEG patterns we can look at what's called your sleep architecture and that's really just how deeply asleep you are. You can you can record this, there's patterns of activity in the brain that show how deeply asleep you are and they're called Sleep oscillations. And they found that when participants were in the rocking bed their sleep oscillations showed that it sped up your entrance into a deep sleep. So you fell into a deeper sleep more quickly and also the length of time you spent in that deep sleep was lengthened when you were rocking. And they could correlate this with the EEG activity and it showed that the rocking motion seemed to be synchronizing your neural activity, those sleep oscillations, and synchronizing them together to get you into that deeper sleep and keep you in that deeper sleep for longer.

Katie - This sounds great considering how many people struggle with sleep. Do you think people, companies should be making adult sized rocking beds?

Helen - Well they absolutely should. This sounds like a lovely potential clinical tool for treating insomnia. Even on a population level, if we look at for example our ageing population which is a population that has particular trouble with falling asleep and staying in deep sleeps, this sounds like it could be a really nice mechanical, direct intervention into people's sleep without relying on drugs or other therapies.

Katie – Or, of course, you just go out and buy a hammock.

Helen - Absolutely that'll be fantastic.

Katie - So what else did they find? Because you said before that they were testing memory.

Helen - They also found that participants who had been in the rocking condition that night, the next morning their memory was improved. So this is lovely, this suggests to us that entrance into that deep sleep caused by rocking can improve your memory and it does suggest to us that maybe if you want to improve your memory for a big exam the next day you should sleep in a hammock. The patterns that they were looking at where these sleep oscillations are occurring happen in a part of the brain called the thalamal cortical network. And this part of the brain is really important for consciousness and wakefulness, as we'd expect with sleep, but it's also largely responsible for your memory attention things like that. So it makes sense that this would be linked.

Katie – And, of course, if you get a bad night's sleep most of us have probably witnessed that memory does decline?

Helen – Yes, this is absolutely well documented. So this is a nice route to improving your memory as well as loads of other benefits from getting a good night's sleep.