You probably don’t feel your best when you stay up until the wee hours of the night. But beyond waking up groggy, new research says late bedtimes can actually harm your mental health.
In a recent study published in Psychiatry Research, experts analyzed sleep and health data from 73,888 people in the U.K. Biobank. Those who regularly went to bed after 1 a.m. were more likely to experience mental health disorders like depression and anxiety than those who went to bed before 1 a.m.
It didn’t matter if subjects classified themselves as early birds normally or night owls (this is also known as your chronotype) ― going to bed after 1 a.m. hurt people mentally, the study found. In fact, night owls who went to bed after 1 a.m. were most likely to have mental health impacts. People who went to bed before 1 a.m. had the lowest amount of mental health diagnoses.
This study has some limitations: The people who make up the U.K. Biobank are mostly white and middle-aged or older, according to Dr. Indira Gurubhagavatula, a professor of medicine in the division of Sleep Medicine at the University of Pennsylvania, who is not affiliated with the study.
“And the way they decided which chronotype you are came from a single question, although they did use one that has been validated. But typically how we assess morningness or eveningness is with a much more thorough questionnaire that has a lot more detailed questions,” said Gurubhagavatula. Meaning, whether folks are really morning people or night owls may not be totally accurate in this study.
Additionally, researchers relied on mental health diagnoses data added by doctors. This type of reported data can be inaccurate or doctors can miss a diagnosis, Gurubhagavatula said. That said, she noted that the findings align with what she’d expect and said this study should be recreated in other populations, too.
Going to sleep late has many negative impacts on your mental health — and overall health.
“Generally speaking, if you’re not going to bed until after 1 in the morning or 2 in the morning, it’s very likely you’re not waking up until several hours after the sun has come up. And you’re not going to bed for several hours after the sun has gone down, so I think it gets that this issue … being out of alignment with the environmental light-dark cycle as potentially problematic,” said Matthew Lehrer, an assistant professor in the University of Pittsburgh Department of Psychiatry, who is not affiliated with the study.
It’s important for our bodies to get strong signals that it’s daytime, which can come in the form of morning sun. If you aren’t getting those signals or are getting mixed signals, it can cause issues with your biology, which could also affect your brain, said Lehrer.
“The authors also mentioned that there are some brain-related mechanisms beyond circadian misalignment. Greater nighttime activity is associated with more impulsive and maladaptive behavior,” Lehrer said. “There are some mechanisms in the brain related to behavior and impulsiveness and inhibition … when you’re awake for longer and later, those things tend to decrease and so that could be associated also with poor mental health.”
Gurubhagavatula noted that some brain functions are more vulnerable to sleep loss than others.
“So, for example, maybe you can chew gum, you can talk, you can walk, but the frontal lobe of the brain is very vulnerable to sleep deprivation,” said Gurubhagavatula. The frontal lobe is responsible for a lot of our brain’s functioning, including mood and emotional regulation.
“So, our ability to not swing wildly from one emotion to the other ― that ability to inhibit ourselves ― becomes impaired under conditions of sleep deprivation or staying up very late at night,” Gurubhagavatula said. “Then it can lead to more negativity, more anxiety ... because the higher brain functions that would regulate those emotions are more dulled.”
What about people — like shift workers — who have to go to bed after 1 a.m.?
This can all sound pretty disheartening, especially if you have a job that requires you to go to bed after 1 a.m. Both experts said there are things you can do to minimize the negative impact of a late bedtime and get more sleep, too.
Napping is the first step. “One type of nap is called a strategic nap, which happens during the shift when you know that you have a slump period where it’s so hard to stay awake, your eyes are just going to close. It will be very efficient to use that time to grab a nap if you can,” Gurubhagavatula said.
“And then the other thing is what’s called a preemptive nap. So before the shift even starts, you go into the shift as well rested as you can be,” Gurubhagavatula said, noting that it’s best to keep your naps to 20 or 30 minutes.
Another strategy for night shift workers is “appropriately timed bright light exposure during working hours, if possible,” said Lehrer. “This would be artificial light, such as light boxes for individuals with seasonal affective disorder … they’re very bright, they do have fatigue-reducing and mood-boosting properties.”
Following a specific eating schedule is important, too. “Maintaining more of a daytime-oriented eating schedule can also be helpful, potentially for mood. It’s been shown in simulated night shift work. People in the lab ate their meals during the daytime and they had better improvements in mood relative to those who ate at nighttime,” Lehrer said.
Having a cool, dark and quiet bedroom can help you get better sleep, too, according to both experts.
Beyond this, if you just can’t seem to get the recommended seven to nine hours of sleep, Gurubhagavatula said it’s important to be aware that you could have a sleep disorder. In this case, going to a sleep specialist is a good idea.
“I think that most people by now are starting to understand that as much as we treat sleep like it’s a bonus, it’s actually essential. It’s a biologic necessity,” said Gurubhagavatula. “And we can’t go without it similar to air, food and water.”