Pretty much everyone knows what it’s like to be abruptly woken up from a terrible dream. Even as adults, we experience this from time to time — but could these nightmares be affecting more than just your sleep?
A recent study in Germany says the answer is most likely yes.
What did the study find?
In the study, researchers looked at CAR measurements of 30 volunteers who reported having frequent nightmares for two weeks. The study participants provided saliva samples and reported back on their sleep, particularly if they had any nightmares. The researchers compared CAR measurements after reported nightmares to the ones collected after an uninterrupted night’s sleep.
The CAR is a natural part of waking when cortisol levels are the highest (usually around 9 a.m.), to give us an energy spike to start our day. The study revealed that, after a nightmare, CAR levels were even higher than normal. Not only that, but participants also reported a decrease in mood and overall health that carried into the day.
“This has important methodological implications for CAR studies in general,” the study authors noted, “and might have even more relevance for studies in clinical populations suffering from chronic sleep disturbances.”
Previous studies have supported similar claims. In fact, any disturbance in sleep can result in cortisol levels being affected the next day, which can start a vicious cycle of anxiety during the day causing sleep disturbances at night and so on.
“Dreams can be positive or negative, and there’s no question that nightmares have ramifications that last even after you wake up,” the Sleep Foundation reports. “Falling back asleep after awakening from a nightmare is tough, and those scary images can affect your mood and behavior the next day, causing the equivalent of a bad-dream hangover.”
Our sleep-wake cycle follows a 24-hour circadian rhythm, which we’ve adapted so we sleep at night and are awake during the daytime. Our body’s cortisol production follows this same rhythm. So, when it is disturbed, it can throw off our entire sleeping and waking schedule.
According to Healthline, Cortisol is a hormone produced by the hypothalamic-pituitary-adrenal (HPA) axis. When we are in stressful situations, the HPA axis triggers the release of cortisol. This often results in several bodily responses, such as increased heart rate, rapid breathing, and sharpened sense. It also triggers your fight or flight response, as well as affects mood, digestion and immune system.
While all of this is helpful in dangerous situations, it’s not very helpful when you’ve only experienced a nightmare and need to move on with your day. An overly active HPA axis can lead to regular disruptions in your sleep cycle. So, if you’ve had a bad dream and your cortisol levels increase, it could trigger even worse sleep the next night, continuing the disruption of cortisol production.
“Studies have shown that insomnia and other forms of sleep deprivation cause your body to secrete more cortisol during the day, perhaps in an effort to stimulate alertness,” Healthline reports.
What can you do after you have a nightmare?
Obviously, you don’t want to continue on with this cycle, but how can you stop yourself from having a nightmare? While it may seem out of your control, there are some things that may help.
One 2011 study published in the journal Sleep and Biological Rhythms found that staying up late may be a cause of nightmares.
Researchers suspected that this was due to a possible connection to cortisol levels.
“The idea is that if your sleep has been shifted you may be asleep when cortisol is elevated, which might lead to nightmares or bizarre and vivid dreams,” sleep expert Jessica Payne said.
There are a number of other things that may trigger a bad dream. Late-night snacking, changes in medication, alcohol withdrawal, anxiety, PTSD, and sleep deprivation can all contribute.
When your cortisol levels and sleep are disrupted, it can lead to a number of health issues, including high blood pressure, mood disorders, compromised immune system, digestive issues, and weight gain.
If you are having nightmares regularly, this could be due to a larger sleep disorder and you may want to talk to a doctor.
However, if this is only happening every once in a while, there are some other strategies you can implement to lower your cortisol levels and get you sleeping soundly again.
Try modifying your diet to eliminate foods that trigger cortisol production (skipping coffee in the morning may help). You could also try incorporating more exercise, taking supplements, meditating, or working with a therapist.