What happens in the deepest level of sleep?

Deep sleep: It’s a trending term popping up in online health articles and branded on everything from nighttime supplements to pillow sprays. But what exactly is it, and do you need to worry about it?

Deep sleep defined
Deep sleep is a restorative, non-rapid eye movement (REM) sleep. It’s the third and last stage of non-REM sleep and is considered the deepest stage — hence the name.

During this stage, your muscle tone, pulse and breathing rate decrease and you are more difficult to awaken. It is critical to body recovery and growth and can help to improve your immune response.

“The brain is most rested during this time. It’s where memories are consolidated and could be regarded as photographic memory sleep,” explains Dr. Gary Levinson, a board-certified internal medicine and sleep medicine doctor with Sharp Rees-Stealy Medical Group.

Measuring deep sleep
Knowing that deep sleep plays such an important role in our sleep cycle, you may wonder if there is a method to measure how much you’re getting each night?

According to Dr. Levinson, the principal way to study deep sleep is via a monitor, known as a polysomnogram, which records brain waves. For many of the population, however, this type of testing is unnecessary as it is reserved for diagnosing more complex sleep issues.

And those current, popular sleep trackers on the market? “They cannot track deep sleep,” Dr. Levinson says.

Without high-tech equipment to rely on, how can we know if we’re getting enough of the deep sleep stage? In general, the first and best practice to start out with is to simply develop good sleep habits. Establishing a healthy sleep routine will help ensure you’re properly cycling through all the stages of sleep, not just deep sleep. These other stages of sleep are important as well.

“REM sleep is very restorative too,” Dr. Levinson says. “This is the active dream state for the brain. In fact, in many instances, losing REM sleep — as opposed to losing deep sleep — would almost make you feel worse the next day.”

Conditions affecting deep sleep
While the amount of deep sleep one gets tends to decrease with age, primary sleep disorders and secondary causes can also disturb sleep. Primary sleep disorders include conditions such as sleep apnea or chronic insomnia, while secondary causes range from pain produced by diseases, such as diabetes or arthritis, to an overactive bladder.

Even staring at screens from phones, computers and televisions before bed can qualify as a secondary cause disturbing sleep. Determining if any of these could be the culprit of your restless nights and then working to address them may help improve your overall sleep pattern.

Telltale sign you need better sleep
If you’ve tried a variety of strategies for better sleep and nothing seems to be working, when should you reach out to your doctor? The answer lies in a surprisingly low-tech indicator.

“You seek help when it’s affecting your quality of life, those activities of daily living,” Dr. Levinson says. “A sleep disorder becomes a disorder when it affects daytime behaviors or sparks consequences.”

In other words, there’s a problem if your restless nights continue and you find yourself falling asleep at work, getting drowsy behind the wheel or unable to concentrate on tasks. It’s worth it to check in with your medical provider so you can get back on track to wakeful, rested days.

If you think you might be suffering from a sleep disorder, visit the Sleep Center at Sharp Rees-Stealy for more information.