Deep Sleep: Its Importance and How to Achieve It
Deep sleep supports the restorative functions necessary to feel your best every day. Getting enough deep sleep helps the brain and body prepare to absorb new information and adapt to new environments. If you don't get enough deep sleep, it can cause learning difficulties, make you susceptible to infections, and put you at risk for long-term health problems.
What is Deep Sleep?
Deep sleep, also called slow-wave sleep, is when electrical activity in the brain manifests in long, slow waves called delta waves. These waves have a frequency of 0.5 to 2 hertz and must constitute at least 6 seconds of a 30-second window for this period to be considered deep sleep.
Typically, a person falls into deep sleep within an hour of falling asleep and goes through progressively shorter periods of deep sleep as the night progresses. During deep sleep, bodily functions such as breathing and heart rate are also very slow, and muscles are relaxed. It can be difficult to wake someone, and waking up from deep sleep can make you feel disoriented for up to an hour.
How Much Deep Sleep Is Enough?
To determine how much deep sleep you need, first determine how much sleep you need overall. Most adults should aim for at least seven hours of sleep each night. Up to 20% of this time is usually spent in deep sleep.
The body, to some extent, regulates the duration of deep sleep itself. For example, you may spend more time in it if you are recovering from a period of sleep deprivation. Conversely, people who take short naps during the day may get less deep sleep at night, as some of their need for it has already been met during the day. As people age, they typically sleep less in Stage 3 (deep sleep) and spend more time in Stage 2 (light sleep).
Why Is Deep Sleep Important?
While all stages of sleep are necessary for good health, deep sleep offers specific physical and mental benefits.
Physical Benefits:
Your body releases growth hormone, which helps build and repair muscles, bones, and tissues. Deep sleep also aids immune system function. It can be important for regulating glucose metabolism. Elite athletes value deep sleep as it helps restore energy reserves.
Mental Benefits:
Deep sleep is important for cognitive function and memory. It is thought to play a role in language acquisition, motor skills, and brain development. Throughout the day, you receive informational cues that strengthen synapses (communication points) in your brain network. However, your brain cannot continuously absorb information without rest, so scientists suggest that deep sleep plays a role in preparing your synapses for the next day. In other words, your brain evaluates new memories and then retains and consolidates only the most relevant ones to avoid overloading memory pathways. Although this theory is still being researched, evidence suggests that people get a greater proportion of deep sleep after learning a new task and show higher concentrations of slow waves in brain areas associated with the task.
Tips for Getting More Deep Sleep
Healthy sleep habits include:
- Regular exercise
- Reducing caffeine intake in the afternoon and evening
- Ensuring a quiet, cool, and dark sleep environment
- Creating a relaxing bedtime routine
Here are some additional steps you can take to encourage deep sleep:
Take a warm bath: Warming your body at least an hour before bedtime can help induce slow-wave sleep. The warmth from the bath draws heat to your hands and feet, which then dissipates. The process allows you to cool down to a comfortable temperature for sleep.
Change your diet: What you eat and drink before bed affects your sleep. One study found that people who consumed a diet high in saturated fat got less slow-wave sleep. People who consumed more fiber were more likely to have deeper sleep.
Listen to binaural beats: These are created by listening to two slightly different tones, one in each ear. The difference between the frequencies of these tones creates a perceived third tone, or binaural beat. Limited research suggests that listening to delta wave binaural beats may help induce delta waves in the brain and therefore Stage 3 sleep.
To ensure you get quality rest, also consider steps such as purchasing a new pillow or mattress.
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