Deep sleep is when your body clears toxins from your brain — here are 6 ways to get more of it

• Deep sleep is the phase of sleep responsible for cell repair, clearing toxins, and processing info.
• You can get more deep sleep by taking a hot bath before bed and avoiding caffeine and alcohol.

Getting enough sleep, about eight hours per night, is vital for your health, but it's also important to get good quality sleep.

Each night, your body moves through an average of four to six sleep cycles — each cycle lasts about 90 minutes and is made up of four different stages:

• Stage 1 (1-5 minutes): The period where you transition into sleep, and your heartbeat and breathing start to slow.
• Stage 2 (10-60 minutes): The period of light sleep in which your heart rate and breathing continue to slow.
• Stage 3 (20-40 minutes): This stage is called deep sleep because it's the deepest sleep you get during the night. Your brainwave frequencies slow down and it's difficult to wake up from this stage.
• Stage 4 (REM) (10-60 minutes): Rapid eye movement (REM) sleep is the stage in which you have most of your dreams. Your brain is active and your eyes move quickly under your lids.

All stages of sleep are important, but "deep sleep is essential for the optimal functioning of both the body and the brain," says Girardin Jean-Louis, PhD, a sleep researcher and psychiatry professor at the NYU Grossman School of Medicine.

You spend about 13%-23% of the night in deep sleep. This means that if you have a normal night of sleep, you should be getting between 55 and 97 minutes of deep sleep each night.

The benefits of deep sleep

Getting enough deep sleep is necessary for your body and brain to perform functions like:

• Processing memories and information: This is especially important for children since so much learning takes place in childhood, says Carl Bazil, MD, PhD, a professor of neurology at Columbia University who specializes in sleep disorders.
• Repairing any damage to your cells: Your body uses this time to repair any injuries you might have gotten during the day and helps boost your immune system, says Jean-Louis.
• Clearing out toxins: "The brain flushes out toxic waste products such as amyloid-β and tau, two important factors implicated in Alzheimer's disease," says Jean-Louis.
• Growing: More human growth hormone is released during deep sleep than during any other stage, which can benefit children in particular during their growing years.

Because deep sleep is so crucial for your body, it's important to make sure you're getting enough of it. Here are five key ways you can increase the amount of deep sleep you're getting at night.

1. Exercise

"Exercise can improve sleep by decreasing how long it takes to fall asleep," Jean-Louis says.

Exercise may also help realign your internal body clock and relieve anxiety, which can improve the quality of your sleep and increase deep sleep.

There are a couple of important guidelines for using exercise to enhance deep sleep:

Aerobic exercise like jogging works best to increase your deep sleep. In particular, moderate aerobic exercise like walking may help you spend more time in the deep sleep stage.

If you have insomnia, it's best to exercise earlier in the day, as the hormones released during exercise can stimulate your brain and make you feel more alert.

Exercising on a particular day can help you sleep better that night, and exercising around three times per week can improve your general sleep quality.

2. Take a hot bath

Taking a hot bath increases your core body temperature, which then drops when you get out of the tub. This temperature change is similar to what happens as you fall asleep, so it signals to your body that it's time to go to sleep, Jean-Louis says.

A 2019 review found that taking a hot bath before bed can help you fall asleep faster and increase your deep sleep, though the researchers note that more studies are still needed.

To take a hot bath for sleep, Jean-Louis offers these tips:

The bath should be between 104 °F to 109 °F.

It works best to take the bath about one and a half hours before bedtime.

The bath should last for at least 10 minutes to give your body time to heat up.

3. Don't drink caffeine close to bedtime

Drinking a caffeinated beverage like coffee or tea increases the activity of your brain and nervous system, which can make it harder to get deep sleep.

"Caffeine can decrease all stages of sleep and cause sleep disruption," Bazil says, and the effects of caffeine may last longer than you think. "Even taken mid-day or as early as noon can interfere with sleep," says Bazil.

A 2016 review found that people who had caffeine experienced reduced deep sleep, particularly if it was within a few hours of bedtime.

4. Try white or pink noise

There are several types of noise that may help increase your deep sleep, including white noise and pink noise.

White noise is a type of noise that contains all of the audible frequencies of sound, and plays each frequency at the same volume. People often say that it sounds like TV static.

Experts still aren't sure why white noise improves sleep, but it may help alter your brain waves or just block out background noise.

White noise may also help alleviate any nighttime anxiety that could make it harder for you to fall or stay asleep. This means you're likely to sleep for longer and have better sleep quality, says Jean-Louis.

Pink noise is similar to white noise — it contains every frequency of sound, but the frequencies become quieter as the octaves get higher. This means that it has a lower pitch compared to white noise — some compare it to the sound of a waterfall.

More research is still needed, but early studies suggest that listening to pink noise while sleeping may help increase your deep sleep.

5. Get more sunlight

"Sunlight is particularly important for keeping your biological clock set," Bazil says. This is important because disruptions in your body clock can interfere with deep sleep.

Getting sunlight in the morning "can signal your body that this is wake time, and then when bedtime rolls around you're ready to sleep better," says Bazil.

A very small 2014 study instructed participants to get 30 minutes of sun exposure at 11 am each day for six weeks. The results showed that people who got sunlight had better quality sleep, compared to people who didn't add sunlight to their routine.

Insider's takeaway

"Quality sleep is at least as important to your health as exercise and nutrition," Bazil says. Deep sleep in particular is important for learning, growing, and repairing cell damage.

There are several science-backed methods you can use to increase the amount of deep sleep you're getting, including listening to white noise, skipping afternoon coffee, and getting morning sunlight.

Changing your habits "requires some time and effort especially if you are having difficulty, but it's worth it," Bazil says.