Neurologist Alejandro Iranzo: ‘Sleeping is like a recycling bin with memories that you store or throw away’

Sleep provides clues about the state of our health. And just as good sleep underpins one of the pillars of physical and mental well-being, problems falling asleep and the quality of our sleep serve as a guide for doctors to detect hidden pathologies or those that are yet to come. Even nightmares offer information. Dr. Alejandro Iranzo, a neurologist at the Hospital Clínic in Barcelona (Spain), says that after years of research, his team discovered that REM sleep behavior disorder can reveal the first signs of Parkinson’s.

“We are paralyzed during the REM phase of sleep. The brain tells the muscles not to move because we are dreaming. But there are people over 50, who have a REM sleep behavior disorder, in which that part of the brain does not work, and they can move in the nightmares. They talk, they scream, they kick, they fall out of bed, swear, and so on. And we have seen that, five years after diagnosis, 25% develop Parkinson’s disease; and 10 years after that, it is 75%. It is the beginning of Parkinson’s disease or dementia, which, instead of starting with memory problems or tremors, begins with a sleep disorder,” the neurologist, who is head of the Sleep Unit at the hospital, says.

Iranzo is a professor at the University of Barcelona (UB) and has just started as chair of sleep at the newly created UB-Adsalutem Unit, a department to encourage teaching, training, research, and the communication of sleep disorders. “Sleep is important for living, but it is little known: we do not know very exactly how it works and what importance it may have for the patient’s quality of life if it does not work,” he says.

Question. How has our sleep evolved?

Answer. There is a lack of sleep epidemic. Depending on our age, it is advisable to sleep between seven and nine hours. And when you do population studies, you see that 24% sleep less than recommended. These are people who cannot sleep or who lose sleep at bedtime. On average, we now sleep six hours less per week than 18 years ago, and if we compare it with 25 years ago, we sleep even less.

Q. Where is the line between sleeping poorly and having a sleep disorder?

A. The patient who is suffering the consequences of a lack of sleep comes to the hospital or complains to the doctor. They’re unable to concentrate, and they feel exhausted, sleepy, irritable, dejected, depressed, or anxious because this lack of sleep means they are emotionally unstable, they perform tasks poorly, and they are not well rested.

Q. Does dreaming influence the quality of sleep?

A. No one chooses what they are going to dream about, and no one decides if they are going to remember it or not. We tend to play down [the content of] our dreams. The thing is, obviously, people who have a lot of nightmares are terrified of going to sleep. Then, there are other nightmares that tell you if you may have this or that illness.

If I dream that I have to escape from an accident or that a train is going to hit me and I have to run away, this is typical of sleepwalking. If I dream that I can’t find the car where I left it in the parking lot or if the boss gives me a lot of work and I can’t finish, it could be typical of apnea. If it is a dream that someone is coming to attack me and I have to defend myself, it could be a REM sleep behavior disorder. We don’t know why, but the type of dreams a patient has acts as a guide to what type of illness they may have.

Q. What is good sleep?

A. First, [you have to look at] the amount of sleep: try to use between seven and nine hours as a base. And know that if you are sleeping more than 10 hours something is going on, and something else is happening if you sleep less than six hours. Next, [you have to look at] the quality of sleep, which you can infer or estimate simply when you wake up: Do you wake up feeling like you’ve recharged your batteries?

“We don’t know why, but the type of dreams tells us what type of illness a patient may have.”

Q. Is sleeping well a kind of “reset” in the brain?

A. What you see at the brain level (using animal and neuroimaging studies) is that some cells are replenishing, some are resting, and others are fixing themselves. And then, at the level of memory, those memories that do not matter are also being discarded. Sleep is like a recycling bin, with memories you throw away and others you store. And then, it is also important at the level of emotional, hormonal, endocrine, and immunological stability. When you don’t sleep, you have poorer concentration, you’re more irritable, more depressed, more prone to everyday infections, more hormonal disorders, and so on.

Q. How far can the damage done by sleeping poorly go?

A. In the long term, there is a direct association — and sometimes it’s bidirectional — of little or poor sleep, with obesity, hypertension, diabetes, high cholesterol, some types of cancer, and some neurodegenerative diseases such as Alzheimer’s.

Q. Are anxiolytics friends or enemies?

A. These medications are given for insomnia. The drugs we have for falling asleep are quite good, but the vast majority of them are addictive and build up a tolerance to them. They work well for you, but after a while, they don’t, and you have to increase the dose. It is a vicious circle. So, for us, the best thing is to use hypnotic treatment for a few weeks and you have to agree from the beginning that we are not going to treat the problem that is keeping you up at night with medication for the rest of your life.

Q. Is sleeping too much also bad?

A. Sleeping too much is a sign that you sleep few hours or, although you sleep the correct number of hours, they are not of good quality. If a person sleeps five hours from Monday to Friday because they have a deadline on Friday, they will sleep a lot more on Saturday. But, perhaps it is also telling me that this is poor quality sleep because there are apneas when the patient is not breathing. And after each apnea, they wake up for a second or two, which they don’t realize, but it breaks the continuity of their sleep: So, they’ve had a super-fragmented sleep, which is not restful, and these people fall asleep during the day.

There is a lack of sleep epidemic: we sleep six hours less per week than 18 years ago”

Q. Is waking up at night some kind of warning even if you go back to sleep later?

A. No, it is not a pathological problem. Every 20 or 30 minutes we all wake up to change our posture. Waking up briefly, for a few seconds, and then falling asleep is not an illness.

Q. How do eating habits influence sleep?

A. It's common sense: if you eat too late, your stomach is very full and this does not facilitate digestion. In the same way that if you go to sleep full of worries or if you have slept little, with low blood glucose, it does not help you fall asleep.

Q. How have screens changed our sleep dynamics?

A. Ideally, you associate the bed simply with the act of sleeping. During nighttime hours, you need quiet and very little light when you go to sleep. The light from tablet, cell phone, or computer screens reaches your retina and it keeps you alert.

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