How sleep affects mental health (and vice versa): What the science says

This surprised Zeitzer and his colleagues, who thought it would be healthier to live in alignment with one’s “chronotype,” the sleep patterns a person naturally tends toward. In their study, participants who went to bed late had higher risks of depression, anxiety and other mental health disorders, no matter whether going to bed late aligned with their natural sleep preferences.

Zeitzer thinks this could be partly a result of what people are doing late at night, and how poor-decision hangovers could be bad for mental health.

“There is a theory called ‘mind after midnight,’ which is this idea that after midnight, your brain makes choices it wouldn’t make at noon,” he said. “Late at night, there are fewer social guardrails because everyone else is asleep, and you’ve been awake for 16 hours, so the cumulative experiences and stress of the day can change your decision-making processes.”

Which came first, the depression or the insomnia?

Because sleep and mental health are so intertwined, teasing out cause and effect between the two can be tricky. In other fields, scientists often turn to animal studies where they can manipulate the animals’ biology or environments. But similar tactics for studying mental health can fall short, Zeitzer said. There aren’t great animal replicas of most human mental health conditions, and assessing mood in a lab rat is difficult. Instead, researchers often trace the sequence of events. Which came first, the sleep disruption or the depression? Even that might not always indicate that the first caused the second.

“One of the theories is that you have some underlying disruption of the brain where at a lower level of disruption, you get sleep problems. And at a higher level of disruption, you get disruption of emotion,” Zeitzer said. “You see the sleep one first, but it’s really the same process.”

To complicate the picture further, the issues can compound and amplify each other, resulting in a vicious cycle where mental health problems exacerbate sleep problems, which further exacerbate sleep disruptions. In the clinic, sleep specialists observe which symptoms seem to dominate a person’s experience.

“Does it look like the insomnia has taken on enough of a life of its own that it would be helpful to treat independently? Does it look like it’s sticking around even when other things are getting better?” asked Norah Simpson, PhD, a clinical professor of psychiatry and behavioral sciences. “Those would make me think it’s something we need to address.”

(Adobe Stock/Eugenio Marongiu)

Not all sleepers were created equal

In the U.S., 16% of employed people are shift workers, meaning their work hours fall outside the typical 9-to-5. Of those, 6% work evenings and 4% work overnight. The rest work irregular shifts — think on-call doctors and nurses who swap between working days and overnight. Shift work is also associated with depression, anxiety and other psychiatric conditions.

Getting the best sleep possible is especially challenging for these people. So someone switching from an overnight shift to a day schedule, for example, might want to limit their light exposure after their shift, take a few-hour nap when they get home, then stay up until nighttime to return to a regular schedule as soon as possible.

“We’re still really leveraging those two underlying systems, the circadian rhythm and the sleep drive,” Simpson said.

And then there are teenagers. When puberty hits, there’s a natural shift in circadian rhythms; melatonin production in teens is delayed by about two hours compared with that of younger children and adults. But teens need just as much, if not more, sleep than adults do.

Some school districts have shifted start times later in recognition of this biological change. But many remain on an early morning schedule, and sports teams and other extracurriculars often have morning practices or meetings, requiring even earlier rising.

Mental health in teens has worsened since before the pandemic, and symptoms of depression among high schoolers jumped to even higher levels since 2020. Some of this may be a result of a rise in chronic sleep deprivation — up to 80% of teens aren’t getting the recommended amount of sleep. Unfortunately, the pressures of school and extracurricular activities keep sustainable solutions to the combined sleep and mental health crisis out of reach for many.

“The question becomes, if your kid is sleeping until 2 in the afternoon on the weekend, is that OK?” Zeitzer asked. “Frankly, they need that sleep. That is not an ideal sleep pattern. But not getting enough sleep overall is worse.”

(Adobe Stock/Forewer)

Improving the sleep-mental health relationship

For people who want to take steps to improve their mental health through better sleep, Stanford Medicine researchers offer tips for achieving or maintaining good sleep hygiene:

• Avoid caffeine and other stimulants after early afternoon.
• Avoid alcohol before bedtime — it can reduce the quality of sleep and cause more frequent sleep interruptions.
• Keep the bedroom a comfortable and soothing environment.
• Try to go to bed and wake up at the same time every day, even on weekends. Maintaining a consistent sleep schedule is healthier than trying to weekend-warrior your sleep.
• Avoid screen time before bed. Apps are designed to keep you awake and can displace sleep.
• If you can’t sleep, don’t panic. You can’t force sleep when it is not happening. It is better to let go of the struggle and pick up a book and read until you are sleepy.

If sleep issues are lasting weeks or months, it could be time to see a sleep specialist. The problem could be a chronic condition such as sleep apnea, circadian rhythm disorder, narcolepsy or chronic insomnia.

Cognitive behavior therapy is the gold-standard treatment for treating insomnia; it teaches patients behavioral changes to regulate the two biological systems involved in sleep: the circadian system and the sleep drive system.

The latter works much like natural hunger. People need to build up enough “sleep hunger” so they can get to sleep at night. That means avoiding long naps during the day. CBT practitioners also work with patients to address anxiety around sleep and insomnia.

“We work on decoupling the connection between the bed and arousing feelings. When someone has insomnia, they are so aroused and anxious, it prevents them from being able to fall asleep,” Goldstein-Piekarski said. “By decoupling those experiences, to re-pair sleep with the bed, you can more easily fall asleep.”