You probably don’t need scientific evidence to know that lack of sleep makes a person very cranky. And the fact that regular sleep has such a huge impact on a person’s mood is reason enough to make it a priority. The National Alliance on Mental Illness estimates that insomnia influences depression, anxiety and other psychological conditions in at least half of all people who suffer such sleeplessness.
Scientists don’t fully understand why sleep and mood are so connected. One study published in Current Biology looked at the amygdala, which is part of the deep brain located in the temporal lobe. This region is known to play a role in our ability to regulate emotions. For the study, the researchers showed the participants—who hadn’t slept in 35 hours—photos that could be classified as sad. Magnetic resonance imaging revealed the sleep-deprived participants had more responsive amygdalas. But also, the links to other areas of the brain were weaker, suggesting that the reason people who are sleep deprived tend to be emotionally volatile is also due to the lack of response from other mental faculties. In short: Lack of sleep hinders the ability to regulate emotions.
"With poor sleep, thoughts can be more negative and the processing of them may be more likely to include negative repetitive loops, or rumination, leading to negative emotions," says Jenna Carl, a clinical psychologist who specializes in the research and treatment of anxiety, depression and insomnia and the medical director of Big Health, a digital medicine company that created a program known as Sleepio that helps users track their sleeping habits.
A recent paper tested out the program as a way to manage and change poor sleep habits, and found it also appeared to improve mental health of study participants. The study, published in the October issue the Lancet Psychiatry, involved more than 3,700 college students who used the Sleepio program, which is based on cognitive behavioral therapy (CBT), a type of psychological intervention that focuses on how thought processes influence behaviors.
The participants filled out self-reported questionnaires about their sleep habits and mental health symptoms such as anxiety and depression and more severe problems such as hallucinations and paranoia. They were randomly assigned to either the test or control group for six weeks. Each participant kept a sleep diary.
The researchers found that at 10 weeks people in the treatment group reported far less insomnia as well as experienced fewer hallucinations, depression, anxiety and paranoia than people in the control group.
It turns out that keeping a consistent sleep schedule and getting at least eight hours a night could also be one of the most effective ways to manage existing psychological conditions. Mental health professionals emphasize the importance of getting plenty of sleep since it's one of the most effective ways to control symptoms of depression, anxiety and bipolar disorder. "Historically, clinicians believed that sleep difficulties were merely symptoms of anxiety and depression, and would resolve when good mental health was restored," says Carl.
But it's also important to remember that changes in sleeping habits can also be a sign of mental health problems. According to the Sleep Foundation, people with insomnia are 10 times more likely to have clinical depression and 17 times as likely to suffer from anxiety.
For people who struggle with bipolar disorder, insomnia is a significant problem. At the same time, lack of sleep can also increase the severity of a person’s manic episode. For that reason alone, sleep disturbance is considered a core symptom of bipolar disorder. "The advantage of sleep is that it is a far less stigmatized topic than anxiety or depression, making it a great starting point for addressing these conditions," says Carl.