These are the most important hours of sleep for your brain, according to an expert

If your mom was anything like mine, she probably told you many things when you were younger that you now question as an adult. While some of the things – like the  fact that worms will crawl out of your ears if you eat too much sugar – were definitely false, others turned out to be backed by experts.

One of the things my mom always used to tell me in order to convince me to go to sleep earlier was that the hours of sleep you receive before midnight are more important than any that you receive after midnight.

Why are the sleeping hours before midnight important?

According to Dr. Nerina Ramlakhan, a sleep expert and author of Tired But Wired: The Essential Sleep Toolkit, every cell in our body is linked to the movements of the Earth and moon, and our body’s circadian timer wants us to take clues from the celestial bodies for when it is time to go to sleep.

“There’s an area in the brain called the circadian timer which helps to synchronise the movement and function of every cell in the body to the levels of light and darkness in the environment,” Ramlakhan told Stylist. “So as the light level drops below a certain limit, it sends a message to the pineal gland through the eyes, and then every cell in the body starts adjusting its functions.”

We learn from a young age that out circadian rhythm plays an essential role in the regulation of many of our bodies systems. A

According to Ramlakhan, the 90-minute phase just before midnight is an extremely powerful phase of sleep because it is the period in which the body is replenished.

“It’s rejuvenated on every level – physically, mentally, emotionally and, I believe, spiritually as well. There’s a lot of healing that takes place in that first phase of sleep,” Ramlakhan said.

In addition to physical rejuvenation, the first 90 minutes of sleep is also important for your brain. This phase is important for reorganizing information in your brain from that previous day. This phase is also important for bringing adrenaline levels down, which means if you are under a lot of stress, you will want to experience this phase before midnight.

How going to sleep late affects your immune system

A study of 26 healthy adults, published by the National Institutes of Health, found that people who have a habit of going to sleep earlier have a higher ratio of lymphocytes, while those with a habit of staying up late show a higher ratio of granulocytes.

Among the participants in the study, 12 people were in the habit of going to sleep before midnight consistently, while 14 people had a habit of staying up late, consistently going to sleep after 2 a.m.

It was found that the group that went to sleep before midnight had a remarkably high ratio of lymphocytes compared to the group that went to sleep late. Lymphocytes are white blood cells that are one of the body’s main types of immune cells. Unusually high or low levels of lymphocytes can be a sign of serious health issues in the body.

On the flip side, those who went to sleep late had a remarkably high ratio of granulocytes when compared to those who went to sleep before midnight. Granulocytes are other types of white blood cells that help fight off infection in the body.

There was no difference observed in lymphocyte and granulocyte ratios due to the duration of sleep, which suggests that the time when a person goes to sleep is more important than the total hours of sleep someone receives during the night.

Jennifer Fabiano is an SEO reporter at Ladders.