The Essential Role of Sleep in Brain Health and in Depression

By Dr. Laura Lewis, PhD, Research Fellow

1907 Foundation

. https://www.1907.foundation/

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The Essential Role of Sleep in Brain Health and in Depression

We all know a good night of sleep affects our mood the next day, but why? Sleep problems are linked to mood disorders, such as depression, suggesting that sleep plays an active role in maintaining healthy brain function. How and why sleep influences brain health is surprisingly not well understood and is an important area of ongoing research with many open questions. Today, MRI scans are changing what we know about our brains and can provide a window into the biological origins of mental health disorders.

Why is sleep integral to how our bodies function?

The scientific community has studied the effect of sleep on our overall health for decades. Studies prove that sleep deprivation decreases our ability to perform many cognitive tasks. Lack of sleep causes fatigue, irritability, difficulty focusing, decreased memory, and mood changes even in healthy individuals.

Mental health disorders are frequently linked to disrupted sleep. Major depression is an all-too-common disorder, and within that cohort, we find many people who have trouble falling or staying asleep. Persistent problems with sleep can exacerbate symptoms into a downward spiral that worsens over time. Sleep disruption may therefore be not just a symptom, but also a contributing component of mental health disorders.

Given the strong connection between sleep and mental health, a key priority for research is to uncover the cause. If poor sleep contributes to mental health disorders, improving sleep might be a promising pathway for improving health. Understanding exactly why and how sleep affects the brain is essential for finding treatments that can target and improve those pathways, and ultimately restore healthy sleep.

How sleep increases waste removal from the brain

During sleep, the state and behavior of our brains are strikingly altered. In recent years, scientific studies have revealed new processes happening in the brain during sleep that may play a critical role in its beneficial effects.

Today, we have unprecedented access to the inner workings of the human brain through brain imaging technologies such as MRI scans. For the first time, we can peek inside the human brain while resting. These techniques are noninvasive and can be used in patients with depression as well.

The brain is enveloped in a fluid called cerebrospinal fluid (CSF), which cushions it, and carries away waste from the brain. Using imaging to look inside the brain, our research has found that large waves of cerebrospinal fluid (CSF) flow through our brains as we sleep. Previous animal studies suggest that this nightly rush of CSF washes away waste products and inflammatory substances. If our brains need CSF flow each night to remove waste, it may help explain one reason why sleep is essential to restoring our brain function each morning. 

Our ongoing research is imaging sleep in patients, aiming to develop a new understanding of how sleep disruption contributes to depression. We want to know exactly why and how sleep restores brain health. Our long-term goals are to identify the exact neurobiological origins of depression and develop therapeutic approaches that will improve mental health.

Current research into depression needs to examine the factor sleep plays in our mental health

Psychologists and psychiatrists frequently examine the emotional and psychological impact of mental illness, but it is difficult for them to access the biological pathways. Symptoms of depression are linked to real chemical and physical changes in our brains. The biology of sleep has an important role in our emotional states and mood regulation. Ongoing research is using a close examination of brain images to understand how sleep changes in patients.

Sleep should be a critical factor to consider when treating depression; however, it is often overlooked, as it can be difficult to measure an individual’s sleep quality. Sleep helps maintain a healthy brain and understanding it is a stepping stone on the path to better diagnosing and treating mental health conditions.

Our research seeks to explore the mysteries in this process and come away with contributions for people struggling with mental health. Studying the effects of sleep and CSF flow not only enables us to understand better our brains and how inflammation is linked to mood, but it has long-term implications for how we treat mental health. When we understand the process fully, we may be able to harness the profound effects of sleep on mood and cognition by developing customized treatments for individual sleep patterns. We have long known the importance of sleep — now, it’s time to better understand its biological reasons and medical implications for our mental health.