Dr. Mark Czeisler has a Ph.D. in Psychology and is currently studying at Harvard Medical School. He’s also a research fellow at the Turner Institute for Brain and Mental Health, and is the lead author of a recently published study on the impact of prior sleep-wake behaviors on mental health during the COVID-19 pandemic.
Is sleeping better for mental health something the average person should be thinking about on a regular basis?
Mark Czeisler: Absolutely, yes. I think about it from two perspectives. First, even in a state of health, there are benefits of sleep for mental performance, like attention and cognition. And then also the consolidation of memories and emotional processing happens during sleep.
And then secondly, for someone who is in a position where they are living with either a sleep disorder or a mental health condition, there’s a strong bi-directional relationship between sleep and mental health–75% of people who have depressive disorder have symptoms of insomnia. The impaired sleep may be contributing to the depression or the depression is leading to impaired sleep, with a combination of both of those factors occurring in most cases.
What are your top 3 things to keep in mind when it comes to sleep’s impact on mental health?
MC: First, I think that there are three pillars of sleep–consistency, duration, and quality, they’re all key elements. Part 1 is optimizing those elements. Screening for sleep conditions or circadian conditions can help. For example, 80% of cases of obstructive sleep apnea, which can have all sorts of consequences, are undiagnosed or untreated.
Part 2 is that there are going to be ups and downs in life. We talk about optimizing sleep, mental health, nutrition, exercise, etc, but recognizing that there are going to be times when achieving the ideal routines and metrics for all of those is not going to be possible.
That’s why the finding that prior behavior and prior sleep patterns can be associated with differences in how you respond to trying times is so valuable (more on this to follow). Building those good behaviors ahead of time can be really helpful for acute times when you are not able to achieve them.
And then the last thing, Part 3, for people who are in a position where they have a mental health condition or a sleep condition, there are different types of effective treatments out there. One is cognitive behavioral therapies, which for people who have depression, anxiety, suicidal thoughts, have shown efficacy in helping to treat those in the long term. They can also in some cases reduce insomnia symptoms, even if not specifically designed for that.
Ideally there would be prevention of the onset of these conditions, but if it does get to the point it’s diagnosable it’s certainly something for which it’s worth seeking treatment. In addition to treating the core challenge, you can improve health overall too.
What happens during sleep that is so critical for our mental health?
MC: A key aspect is really the consolidation of memories and emotional processing. During the day we have the “acquisition phase” of building memories, and then at night we consolidate a lot of those memories into storage.
Much of that processing happens during REM sleep. We process a lot of the emotional memories during healthy REM sleep, which is something that can become dysregulated in the presence of a mental health condition. For someone with depression, one leading hypothesis is that there’s an abnormal pattern of emotional processing during REM sleep.
How does not getting enough sleep negatively affect our mental health?
MC: Insufficient sleep is certainly associated with adverse mental health symptoms, and then also a dysregulation of functional brain activity that’s going on during sleep.
When we miss out on sleep, the amygdala, which is a part of the brain involved in emotional reactions, goes into overdrive. In fact, there was a study using MRI brain scans that found the amygdala was around 60% more emotionally reactive in participants who were in a state of acute sleep deprivation compared to people who were sleeping normally and well rested. So, when you’re short on sleep, your ability to respond to potentially emotionally intensive events is compromised.
And, what’s worse is that heightened emotional reactivity related to amygdala hyperactivity is paired with dysregulation of another brain area called the prefrontal cortex, which is involved in decision making. And so not only do you have an overactive amygdala, which is making you more emotionally reactive, but also the prefrontal cortex is less able to integrate that information and control impulses.
What about naps? Do you think they are beneficial for your mental health?
MC: Naps are always somewhat of a controversial topic. I think a lot of it comes down to a balance between what’s physiologically beneficial versus maladaptive. It can definitely provide positive mental effects, reducing stress, decreasing the risk of cognitive dysfunction, improving memory retention, and specifically helping with retention of episodic memory.
Scheduled naps and consistent naps can be very beneficial. However, if it’s unscheduled, haphazardly napping or falling asleep as needed, then that can be associated with delaying your bedtime or potentially signaling an underlying medical issue.
People with sufficient sleep duration and high consistency before the pandemic had lower odds of experiencing adverse mental health symptoms in the early months of the pandemic, even if their sleep habits got worse during the pandemic.
Those findings were particularly exciting because they demonstrate that at some level that you can prepare and have a “bank” built up, and then in the face of profound stressors or life events – even to the likes of a pandemic – you can fall back to an extent on prior health behaviors, including sleep. That was really encouraging.
What is one thing about mental health you feel is critically important that most of us probably don’t realize?
MC: Depression is the leading cause of disability worldwide. It’s a really high-magnitude health condition that we’re talking about and that’s depression alone, not including all other mental health conditions.
Also, roughly half of all mental health conditions start by the mid teens, and 75% start by the mid 20s. Those years are very formative, so thinking about having support and optimizing a lot of healthy behaviors during the first decades of life is so important for the prevention of the onset of mental health conditions. It’s something that people live with for a very long time, which is part of the reason why it is a leading cause of disability because it’s with you for life.
Improving population-level mental health will require investments at the personal, institutional, community, and societal levels–mental health is health!