How Does Sleep Affect Mental Health?
A lack of quality sleep is known to impair physical health and may increase the risk of conditions such as type 2 diabetes, heart disease and obesity. It can contribute to or exacerbate cognitive and psychological issues, too, including psychiatric disorders such as depression, anxiety and post-traumatic stress disorder (PTSD), and increase the likelihood of suicide.
"Fundamentally, we all must have sleep," said Gerda Maissel, M.D., a New York City-based patient advocate and founder of My MD Advisor. "It's absolutely essential to health and it is so commonly overlooked."
'Sleep is crucial for cognitive, physical and psychological health.'
Between 50 million and 70 million Americans suffer from sleep disorders, and about one-third of adults routinely miss sufficient shut-eye, according to the Centers for Disease Control and Prevention (CDC). Insomnia, the most prevalent sleep disorder, affects at least 10 percent of the world's population, per Cleveland Clinic.
"We all know sleep affects our mental health," said Doreen Marshall, Ph.D., the vice president of mission engagement at the American Foundation for Suicide Prevention in the Atlanta area. "Sleeping too much or too little can inhibit cognitive skills and the ability to cope with stressors small and big, as well as negatively contribute to existing mental health conditions."
Why is sleep important for brain health?
During sleep, the body recovers and regenerates while the brain is hard at work, flushing out toxins and processing and consolidating information and emotional experiences.
This neurological housekeeping helps to form memories and regulates mood and stress levels. The effects can be conspicuous if these processes are interrupted, even for a single night.
"Sleep is the body's way of restoring our mind and body," said Kristen Casey, Psy.D., a clinical psychologist, insomnia specialist and author based in Kansas City, Missouri. "Sleep is crucial for cognitive, physical and psychological health. We are able to manage our emotions and mood better when we are well-rested.
"On the other hand, it's difficult to concentrate when we haven't slept well. Notably, most people experience irritability and sometimes anxiety or sadness when they are exhausted from sleep deprivation. Sleep is a crucial building block for mental and physical well-being. We notice that people struggle with cognitive tasks when they are sleep-deprived. Our brains just don't function as well as they should when we haven't gotten enough sleep."
'If you are having difficulty sleeping, it could be a sign of worsening mental health or lead to negative mental health consequences'
The effects of sleep deprivation are well-documented, Casey said, and range from memory issues to increased stress. In severe instances, sleep deprivation can even contribute to temporary psychosis—or hallucinations and delusions.
To further complicate matters, a lack of sleep can lead to feelings of malaise compounded by cravings for unhealthy foods and a decreased desire or ability to be physically active.
"We may find that our eating patterns are also disrupted, or that we consume sugar and caffeine more and get less exercise when we are not sleeping well," Marshall said. "We may also find ourselves turning to sleep aids or other substances to help with sleep and can develop a dependency on those."
Over time, the fatigue caused by sleeplessness, coupled with the repercussions of a consistently subpar diet and lack of exercise, can create a vicious cycle that's exceedingly difficult to break, experts said. When these effects are paired with existing stress and psychiatric disorders, the feeling of inescapability can intensify.
How can poor sleep contribute to psychiatric disorders?
Experts have long known of a link between sleep difficulties and psychiatric conditions. About 50 percent of people with insomnia have some form of psychological distress, according to the National Alliance on Mental Illness (NAMI), while about 80 percent of people with schizophrenia and 90 percent of people with major depressive disorder have insomnia.
Traditionally, doctors and scientists believed sleep difficulties were a symptom of something else. But experts said there is ample evidence of a bidirectional relationship where sleep difficulties contribute to and result from mental health challenges, creating another vicious cycle.
Psychiatric conditions believed to have a bidirectional relationship with sleep deprivation are numerous.
Attention-deficit hyperactivity disorder (ADHD) is primarily diagnosed in children but affects about 4.4 percent of American adults, according to the National Institute of Mental Health (NIMH). Many females go undiagnosed or are diagnosed later in life, suggesting the actual prevalence rate may be higher. As sleep difficulties are a common symptom of ADHD, evidence indicates insomnia is a risk factor for ADHD and may contribute to the condition's development.
More than 50 percent of people with generalized anxiety disorder (GAD) experience persistent sleep difficulties, according to Harvard Health Publishing, and a lack of sleep can exacerbate symptoms. Similarly, people with insomnia are more likely to experience feelings of stress and anxiety, and evidence suggests sleep problems may contribute to the development of anxiety disorders, including GAD. One study found people with chronic insomnia were 17.35 times more likely to have clinical levels of anxiety compared to people without insomnia.
Sleep deprivation can contribute to and exacerbate symptoms of bipolar disorder. Likewise, the mania and depression characteristic of the condition can profoundly impact sleep.
According to an article published in Clinical Psychology, one study found 100 percent of people with bipolar disorder experienced insomnia during depressive episodes and about 78 percent reported hypersomnia (sleeping too much), which is a common symptom of major depressive disorder. People with hypersomnia often feel persistently tired despite sleeping more than usual.
Most people with depression have trouble with sleep, including an inability to fall asleep, trouble staying asleep, sleeping too much without feeling rested and frequent nightmares. Some reports indicate people with insomnia are as much as 10 times more likely to develop depression than people who acquire adequate sleep. Certain antidepressants, such as bupropion fluoxetine and venlafaxine, produce stimulating effects that can further inhibit sleep.
More research is needed to understand depression and its link to sleep. As such, scientists are investigating how treating insomnia through techniques such as a specialized form of cognitive behavioral therapy (CBT) might help to prevent or alleviate depression.
Research indicates insomnia is a risk factor for eating disorders, and that eating disorders can disrupt sleep. Night-eating syndrome—it may be the result of circadian rhythm dysfunction—is particularly prevalent in people with insomnia. Research has also identified links between sleep deprivation and other, more common conditions, including anorexia, bulimia and binge eating disorder. One study published in December 2014, examined 549 college students and found that 25 percent to 30 percent of people with eating disorders had insomnia, compared to 5 percent of people without eating disorders. Another study of 400 people with anorexia published in March 2010 found more than 50 percent had insomnia. Moreover, research indicates insomnia can exacerbate eating disorder symptoms and inhibit recovery.
Research indicates between 70 percent and 90 percent of people with PTSD experience sleep difficulties and deficiencies. These can result from a variety of issues, such as nightmares, involuntary arm and leg movements, anxiety, and paranoia. Experts believe sleep deprivation is a risk factor for developing the condition and can exacerbate symptoms.
Substance use disorders
According to the National Institute on Drug Abuse (NIDA), substance use can interfere with sleep and insomnia, and sleep deficiencies can raise the risk of substance use and addiction. People who have insomnia may be more likely to self-medicate and use substances to counteract their sleep difficulties and associated symptoms. Additionally, neurochemical differences that can contribute to insomnia may make a person more susceptible to substance use disorder, and sleep deprivation can inhibit recovery for those who develop it.
Suicidal ideation and behaviors
More people in the United States die by suicide than by homicide each year. Depression is the most prominent risk factor, but research indicates persistent sleeplessness can increase the risk of suicidal ideation and behaviors, Marshall said. One study published in December 2007 found that, among people with depression, subpar sleep increased the risk of suicide by 34 percent.
More research is needed to understand the intricacies of this relationship but research indicates that a lack of sleep is particularly detrimental to the consolidation of positive emotions. That's in addition to causing or exacerbating mood disorders commonly associated with suicide.
The link between sleep, mental health and sexual well-being
Sleep and mental health go hand in hand with sexual well-being, according to Amy Killen, M.D., a regenerative medicine physician in Salt Lake City and a medical advisor at Joi Women's Wellness. People who are sleep-deprived may feel too tired, irritable or stressed to be intimate, she said. Even if they do have sex, they may derive less pleasure from it.
"Being too tired is the most common reason that people give for not wanting to have sex," Killen said. "Fatigue, often from lack of sleep, but also from feeling overworked and stressed, can have profound effects on your sex life."
Sleep deficiencies can interfere with sex hormones, such as testosterone, progesterone and estrogen, Killen explained. Just a few days of sleeplessness can decrease testosterone levels in males, contributing to decreased libido and an increased likelihood of erectile difficulties. And in females, sleep deprivation's effect on estrogen and progesterone levels can influence menstruation and fertility while diminishing libido and contributing to mood swings, anxiety and further sleep disturbance.
If you're waking up without an alarm and you feel refreshed and fine, then you are getting enough sleep for yourself.
At the same time, inadequate sleep prompts the body to ramp up the production of cortisol, the stress hormone.
"High cortisol levels keep your nervous system in the fight-or-flight mode, but a healthy sexual encounter requires that you are instead in the rest-and-relax [parasympathetic] mode," she said. "Being able to shift your nervous system from fight-or-flight to rest-and-relax is much easier when you are fully rested than when you are sleep-deprived."
Research shows sexual health challenges, such as sleep difficulties, are prevalent for people with existing psychiatric conditions, and the interconnectedness can create another vicious cycle. Escaping fight-or-flight mode is particularly difficult for people with anxiety, for instance. And the inability to do so in intimate moments can intensify feelings of stress and uncertainty with regard to romantic relationships, making it all the harder to relax.
Similarly, erectile dysfunction (ED) can be both a symptom of and a contributing factor to conditions such as depression and anxiety. ED is closely associated with sleep disorders. Moreover, Marshall said, poor sleep can contribute to emotional conflict and relationship problems, heightening stress and hindering intimacy.
It can also impair brain function related to decision-making and impulse control, making some people—particularly those experiencing manic episodes—more susceptible to risky sexual behavior.
How much sleep do you really need?
The general consensus is that most people need about seven to nine hours of sleep, on average, to function optimally, Maissel said. However, experts stressed there is no one-size-fits-all number.
For a small subset of people, Maissel said, five to six hours is perfectly fine, whereas this amount for others would cause significant distress. Quality is imperative regardless of the number of hours spent in bed, experts said.
"For most adults, the CDC and the American Academy of Sleep Medicine recommend seven or more hours of sleep per night to optimize overall wellness," Marshall said. "However, the amount of recommended sleep varies depending on your age, your individual chronotype—which is the internal circadian rhythm that influences your sleep cycle, your body's natural disposition to be asleep or awake—as well as your genetic makeup."
"If you are going to sleep, you're waking up without an alarm and you feel refreshed and fine, then you are getting enough sleep for yourself," Maissel said. "I think our society wants us to do more, do more, do more and makes it hard for people who need to sleep a lot to feel OK. You have to know yourself. If you need an alarm to get you up every day, then you're not getting enough sleep."
In parallel, various degrees of sleep deprivation can impact people differently—and some are more sensitive to it than others.
Casey said consistency is the most impactful factor. Although a single night of subpar sleep can produce noticeable effects, persistent sleep issues over days or weeks can accumulate "sleep debt," which is more likely to produce a marked impact.
"Sleep debt is the hours of sleep we never got," Casey said. "We can't necessarily make up for lost sleep, so these hours are pretty much a lost cause. However, people can prioritize their sleep by creating opportunities to hop into bed at a certain time, waking at the same time each day, exercising regularly and maintaining their overall health, which includes mental health."
Speak with a doctor about sleep difficulties
Experts recommend that anyone struggling with insomnia, sleep difficulties or mental health challenges should speak with their doctor to receive a diagnosis and individualized treatment recommendations. Practicing healthful habits, including good sleep hygiene, can provide help.
"While it is important to seek medical advice—that is, to talk to a primary care doctor—if you are experiencing sleep difficulties, there are also things you can do to help promote better sleep," Marshall said.
She mentioned research shows that all of the following can improve the quality and quantity of one's sleep
- Have a structured sleep schedule by going to bed and waking at about the same times each night and day.
- Eliminate the use of electronics in the hours leading up to bedtime.
- Get adequate physical activity and sunlight during the day.
- Don't consume caffeine or alcohol before bedtime.
- Sleep in a dark, cool room.
"What's important to note is that if you are having difficulty sleeping, it could be a sign of worsening mental health or lead to negative mental health consequences," Marshall said. "So it's important to address sleep difficulties with your doctor if they occur on a regular basis and do not respond to lifestyle changes."