How Much Deep Sleep Do You Need?

We hear a lot about sleeping lightly or being in a deep sleep - but there's quite a complicated science behind these common phrases. Many of us are not getting enough deep sleep, and its absence is present in their struggles during the day. 

Here is everything you need to know about deep sleep - from how it is defined, how much you need, and what you can do to improve it.

Deep sleep refers to a specific stage in the sleep cycle that is important for brain function, memory, and productivity during the day.

MedicalNewsToday defines four stages of sleep:

1. A short period of light sleep, during the process of falling asleep. The body begins to relax its muscles and slow its breathing.
2. A transitional period between light and deeper sleep where breathing, heart rate, and brain waves slows farther.
3. Deep sleep phase - the most difficult phase to wake up from. The heart rate and breathing rate are at their lowest and most regular during this stage.
4. Finally, an REM (Rapid Eye Movement) stage occurring after approximately 90 minutes asleep. During this time, the eyes will move back and forth while closed, and breathing and heart rate increases. Dreams can be at their most vivid and the muscles as their most relaxed, which can cause sleep paralysis in some.

If you're unsure if you're getting enough deep sleep, your waking life may have some clues that point towards poor quality sleep. 

Signs of a lack of deep, REM sleep include, but are not limited to:

• Feeling groggy when waking up
• Tiredness during the day
• Increased hunger
• Poor productivity, memory, or problem solving
• Low mood or irritability

These are often typically signs that you're not getting enough sleep overall, but if you're getting the daily recommended 7-9 hours of sleep and you're still experiencing these symptoms, it's likely a sign that it's not the quantity, but the quality of your sleep that is the issue.

Although it is possible to partake in an in-depth sleep study to receive a fully personalised report on the depth of your sleep, the most realistic option for most people is either a wearable device or a sleep app.

There are a number of wearable devices that can be used during sleep to track and report on the quality of your sleep, including:

• smart watches such as Apple Watch, FitBit, Gard, Samsung, etc
• subtle smart rings the Oura, RingConn, and Samsung models
• Sleep masks and headbands that closely track brain activity to measure sleep quality

You don't have to splash out on new devices to track your sleep, there are plenty of sleep-tracking apps that work on most current smartphones. These apps, with permission from the user, implement the microphone and accelerometer technology to track movements and sounds to calculate and analyse the depth of your sleep and its duration.

Popular sleep-tracking apps include:

• Pillow records significant noises such as snoring and sleep-talking to provide feedback
• Calm offers sleep tracking along with bedtime stories and calming music to help improve your sleep
• SleepScore uses sonar technology to track audio and motion and provides analysis on its findings

According to experts at The Sleep Foundation, a healthy adult should have approximately 20% of their time asleep in deep sleep. For example, if you got the recommended seven hours of sleep per night, you would need about a minimum of an hour and a half of deep sleep, and up to two hours for a healthy rest.

There are various methods of improving the number of hours of deep sleep you achieve per night, including:

• A better sleep environment, with eye masks, ear plugs, and blackout curtains
• Consistently going to bed and waking up at the same time to establish a routine
• Getting regular exercise and having a balanced diet
• Increasing magnesium intake, either through tablets, creams, or bath salts