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How many times have you been told to “sleep on it” when you have a problem? Probably a lot, right?

Parents usually give this advice, and it’s often shared with love. However, most people never understand that advice because all they want is to go to sleep and not have to assess or think about their options.

But, Harvard Medical School’s professor of psychiatry, Dr. Robert Stickgold, says every human does that. Everyone solves problems while they’re asleep. More importantly, that’s actually what you’re supposed to do. The brain’s nighttime duty is to find connections. That’s why when you wake up, you usually see things differently. It can sometimes feel stressful, but you shouldn’t fight it. Understanding how it all works will ensure you don’t have sleepless nights trying to assess all your problems.

How problems are solved during sleep

Dr. Stickgold says that when you go to sleep, your brain initiates a triage process. It goes through what you did during the day and finds out what you left unfinished. It’s looking for the emotions that took place shortly after (or during) something happened. These memory “tags” indicate to the brain whether there’s more that needs to be figured out and whether the events that occurred are important. So what the brain is essentially saying is that it thinks it can help you out.

Two things help make this happen. When the brain’s prefrontal cortex switches off, which is where executive decision-making happens, including impulse control and rotational thinking. When this occurs, your brain can now freely associate when there are no places ideas can go.

Secondly, when you’re in REM sleep, the serotonin and neuromodulators norepinephrine are also switched off. Norepinephrine is what enhances concentration on concrete, immediate problems. Dr. Stickgold says it’s the reason why most people don’t want to hear about a new fantastic idea when they’re approaching a deadline.

With that said, there’s not a lot known about serotonin when it’s switched off. However, the doctor suggests it pushes the brain to find valuable looser connections.