How Much Deep Sleep Do You Need?

Slow wave sleep, also called deep sleep, is an important stage in the sleep cycle that enables proper brain function and memory. While most adults are aware that they should aim for between 7 and 9 hours of sleep each night, the science of sleep is quite complex.

The two main categories of sleep are called rapid eye movement (REM) sleep and non-REM sleep, and each has important stages. Humans cycle through these stages in a somewhat regular pattern as they sleep, and a full night’s rest means cycling through these stages a few times before waking up. There may be some ways to get both better sleep and more deep sleep each night, allowing a person to wake up feeling more rested and refreshed.

While a person needs all the stages of sleep, deep sleep is especially important for brain health and function. Deep sleep helps the brain create and store new memories and improves its ability to collect and recall information. This stage of sleep also helps the brain rest and recover from a day of thinking, allowing it to replenish energy in the form of glucose for the next day.

Deep sleep also plays a role in keeping the hormones balanced. The pituitary gland secretes human growth hormone during this stage, which helps tissues in the body grow and regenerate cells. Importantly, a person has to get enough deep sleep for these functions to take place. The amount of deep sleep that a person has will relate to how much overall sleep they get. Sleeping 7 to 9 hours is the recommendation for most adults, which will usually give the body plenty of time in the deeper states of sleep.

If the body does not get enough deep sleep one day, it will compensate the next time it can get sleep by quickly moving through the cycles to reach the deepest levels of sleep faster and stay there longer. However, if the person regularly does not get enough deep sleep, this may start to affect the brain.

As deep sleep plays a role in memory, the body may have difficulty making new memories or retaining information if it does not get enough sleep.

Long-term issues with deep sleep may have an association with other conditions, such as heart disease or Alzheimer’s disease.