Neurons Humming

Wondrous things happen in our brains when we sleep, as the neurons start humming away in sync with each other. In our deep sleep cycles, of which there are several each night, the neurons in our brains synchronize their activity and start oscillating slowly in electronic waves. This is when the brain does its housekeeping, so to speak: it processes new information learned during the day and consolidates our memory. Our body and mind can recover and get ready for the day that lies ahead. “The greater these waves, or the higher their amplitude, the deeper and the more restful our sleep is,” says Angelina Maric. The psychologist and biologist at UZH and the UniversityHospital is researching how sleep affects our health and our brain, in particular.

Poor sleep can affect our performance as well as our health. Getting too little deep sleep can leave us feeling run-over and exhausted the next day. It reduces our ability to concentrate, compromises our impulse control, weakens our immune system and increases the risk of microsleep (falling asleep for a few seconds during the day). And this makes accidents more likely. In the long term, lack of deep sleep puts a strain on the brain, making it more susceptible to neurodegenerative diseases such as Parkinson’s and Alzheimer’s. “To boost prevention, it is therefore important that we make sure we get plenty of proper sleep from a young age,” says Angelina Maric.

Of course, this is easier said than done. Sleep disorders are very common nowadays and can be caused by a wide range of factors. Excessive stress as well as physiological reasons such as restless legs syndrome can prevent people from drifting off into sleep or getting a full night’s sleep. And the older we get, the lighter our sleep becomes. Older people generally sleep less than young people, and not as deeply. 

Sleep disorders can also be brought on by illness. Many people with Parkinson’s or Alzheimer’s have problems sleeping. “Poor sleep is closely linked to both of these conditions,” says the sleep researcher. The negative consequences of this are twofold. First, the lack of deep sleep can lead to an accumulation of unwanted proteins in our blood vessels, which can further accelerate the progression of the neurodegenerative disease. And second, sleep deprivation increases the risk of falls in people with Parkinson’s.

To lower this risk and help curb the disease’s progression, it is therefore important that Parkinson’s and Alzheimer’s patients get a good night’s rest and sleep as deeply as possible. Angelina Maric’s research focuses on helping patients do so through a new medical method. The UZH researcher is involved in SleepLoop, one of the flagship projects of the Hochschulmedizin Zürich initiative, which was set up around six years ago by the sleep researchers and UZH professors Christian Baumann and Reto Huber together with Walter Karlen, who now researches at Ulm University.

The SleepLoop project has brought together researchers from UZH, ETH Zurich and the UniversityHospital Zurich to develop a novel non-pharmacological therapy that aims to improve the quality of patients’ deep sleep. Until now, drugs were the only remedy for sleep deprivation. However, sleeping pills are problematic. They often have unwanted side effects such as daytime drowsiness, and people may become addicted to them. Moreover, they don’t specifically target our deep sleep but affect people’s sleep behavior in a more generalized way. So, while taking sleeping pills may help you sleep, you won’t sleep very deeply. SleepLoop aims to do away with these negative effects.

To achieve their goal, the SleepLoop researchers are developing a device that uses auditory brain stimulation to boost deep sleep. The innovative device consists of a headband with built-in electrodes and headphones which are worn during sleep. The electrodes measure the brain’s activity and forward the data to an integrated microchip, where it is analyzed in real time using custom-developed software. As soon as the neurons in our brain start aligning their activity and the long, slow waves that signal the start of deep sleep emerge, the SleepLoop will play a short faint acoustic signal in the ears of the wearer at regular intervals. The signals are known as pink noise, which sounds like moderate rainfall or ocean waves. These acoustic signals can influence the pattern of our brain waves. “If pink noise is played right before a wave peaks, the wave gets an additional boost and will continue to rise.  In other words, its amplitude increases,” explains Angelina Maric. This deepens our sleep and may help our body and mind regenerate.

The SleepLoop device is a kind of metronome that regulates the electrical brain waves during deep sleep, says the UZH researcher. Studies carried out by the SleepLoop team with healthy test subjects show that the method works and can improve people’s sleep. In a recent study, Angelina Maric was also able to demonstrate a positive effect in Parkinson’s patients. For the experimental study, people with Parkinson’s used the smart headband at home for two weeks – with highly encouraging results. “They were less drowsy in the morning and generally felt better than before,” says the sleep researcher. Despite these promising findings, it’s still not quite clear whether the method will also yield positive effects in the long term and whether it can positively impact disease progression, as the researchers suspect. This is why Maric is now planning a long-term study spanning several years to investigate these questions.

SleepLoop may not only benefit patients with Parkinson’s or Alzheimer’s, but also help to treat depression. The auditory brain stimulation that makes sleep deeper can also be used to do the opposite.  If the acoustic signals are played shortly before a wave reaches its lowest point, the deep sleep wave that follows is stunted. In other words, the wave will be less high, and the patient’s sleep will therefore be lighter. This effect could be used to treating symptoms of depression. “Studies have shown that deep sleep may be too pronounced in certain brain regions in people who suffer from depression, and sleeping less deeply could alleviate their symptoms,” says Angelina Maric. A team of researchers at ETH is currently investigating whether and how this could be achieved using SleepLoop.

No fewer than 16 teams from a broad range of disciplines including neurology, psychiatry and biotech are involved in SleepLoop, and their research is in full swing. At the same time, the spin-off Tosoo is working on developing a commercial product based on the SleepLoop method. “Unlike other sleep stimulators that are already available in the lifestyle sector, SleepLoop is based on extensive research and geared towards clinical application,” says the sleep researcher. There is still a while to go before the medical device becomes widely available to ramp up or curb the deep sleep of patients – and their tossing and turning can be put to an end.