It is no wonder that sleep is an important time for your body to recover and re-energize. With that being said, most individuals undergo different sleep stages each night. This means you spend different amounts of time in several sleep stages, and as a result, you may wake up still feeling tired, or if lucky, you’ll open your eyes feeling energetic and ready for the day.
In this article, you will gain a better understanding of one of the sleep stages, which is the deep sleep, and learn what percentage of sleep should be deep for optimal rest. But if you often find yourself waking up groggy or unfocused, you should improve your deep sleep. Having a cool, cozy environment or using a baby white noise machine could help promote deeper and longer rest.
Decoding Sleep Cycles: A Quick Review of REM, Light, and Deep Sleep
Usually, a sleep cycle lasts about 90 minutes, and within that time, you move through five stages of sleep. The first four stages include the non-rapid eye movement (NREM) sleep, and the fifth stage is when rapid eye movement (REM) sleep happens.
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NREM Sleep
Stage 1 of NREM sleep goes on for several minutes as you transition from being awake to being asleep. In this stage, your heartbeat and eye movements begin to slow down. Your muscles also tend to relax with only occasional twitches, and your brain waves 1begin to slow down from their wakeful state.
Stage 2, on the other hand, comprises about 50 percent of your total sleep cycle. This is where you may fall into more than any other throughout the night. During this stage, your body’s systems continue to relax and slow. Your body temperature drops, and your eye movement stops. In this stage, your brain waves are slow, but you still experience some short bursts of activity.
Stages 3 and 4 are the stages where you experience deep sleep. In these stages, your breathing and heartbeat are at their slowest as your muscles relax. Your brain waves also become the slowest. It is difficult to wake you up at this stage, even with loud noises.
Deep sleep, also known as “slow wave sleep”, where the early stage of deep sleep lasts for about 45-90 minutes. In the first half of the night, it lasts for longer periods and becomes shorter with each sleep cycle.
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REM Sleep
Stage 5, or the first stage of REM sleep, happens for about 90 minutes after moving through NREM stages. During this stage, your eyes move rapidly from side to side, and you experience dreaming as your brain activity increases to a more wakeful stage. Your heart rate also increases to near its wakeful state, and your breathing becomes faster and may be irregular at times.
Defining Deep Sleep: Why Slow-Wave Sleep is Your Body’s Restoration Center
Deep sleep, or the slow-wave sleep, is the most restorative stage of your sleep cycle and is especially helpful for brain health. Your first period of deep sleep each night generally lasts between 45 and 90 minutes. As the night deepens, periods of deep sleep become shorter in the cycles that follow.
Stage 4, in particular, is known as the healing stage of sleep. Tissue growth and repair take place, hormones are released, and cellular energy is restored. In fact, 95 percent of human growth hormones are produced during this stage. During this stage, a variety of functions take place in your mind and body, including:
- Physical recovery occurs
- Consolidated memories
- Learning and emotions are processed
- Blood sugar levels and metabolism balance out
- The immune system is energized
- Your brain detoxifies
Without enough deep sleep, these functions cannot take place, and the symptoms of sleep deprivation kick in.
The Ideal Range: What Percentage of Your Night Should Be Spent in Deep Sleep?
For healthy adults, 13 to 23 percent of sleep should be deep sleep. For an average of 8 hours of sleep, that is roughly 60 to 110 minutes spent in deep sleep. Moreover, most adults spend close to 25 percent of each night in REM sleep.
Some individuals, however, may find they need more hours of sleep in order to feel fully rested and consider it a good night’s sleep. In fact, there is no such thing as too much deep sleep.
Age and Deep Sleep: How Your Need for Restoration Changes Over Time
As mentioned above, in adults, around 13 to 23 percent of total sleep is deep sleep. However, as you get older, the amount of deep sleep naturally decreases. This change is a normal part of aging; your body doesn’t require as much deep sleep for physical restoration as it once did, though quality sleep remains just as important for overall health
Children and babies need more sleep than adults. Babies need the most, spending about 16 of every 24 hours asleep. As children grow older, the amount of sleep they need varies by age:
- Toddlers: 11 to 14 hours
- Preschoolers: 10 to 13 hours
- School-aged children: 9 to 12 hours
- Teens: 8 to 10 hours
The Power of Delta Waves: Deep Sleep’s Role in Physical Repair and Growth Hormone Release
Your brain produces slow, rhythmic electrical patterns known as delta waves during deep sleep. These waves are the slowest brainwaves, which signal that your body is in its deepest and most restorative stage. In addition, it serves as a cue for your body to start the repair processes that keep you healthy and energezied.
Also, during this stage, your pituitary gland produces human growth hormone, the hormone responsible for cell generation, tissue repair, and muscle growth. Without enough deep sleep, your body produces less hormone, which can result in slower healing and reduced physical performance.
Too Much or Too Little? Interpreting Deep Sleep Data from Wearable Trackers
With the technology progressing rapidly, you are able to track how much time you spend in each stage of sleep. While this date can be helpful, it is also important to interpret it with moderation.
Most wearable trackers on the market track sleep movement, heart rate, and even oxygen levels; however, they aren’t always a hundred percent accurate.
If your tracker shows much less than the 13 to 23 percent of total sleep in deep sleep, it could mean there are factors affecting your sleep quality, such as stress, caffeine, or an inconsistent sleep schedule. But if you get more deep sleep than average, it may indicate that your body is making up on rest or recovering from physical exhaustion.
Remember to use the tracker as a guide and do not entirely depend on it. Aim to have consistent and restorative sleep habits to make you feel more refreshed and energized in the morning.
Simple Hacks to Boost Your Deep Sleep Score Tonight (Exercise, Diet, and Timing)
You can’t increase the amount of your deep sleep in an instant, but there are simple hacks you can do to boost your deep sleep score, including:
- Create a sleep-friendly environment
- Stick to a sleep schedule
- Limit alcohol and caffeine
- Avoid heavy meals before bed
- Exercise regularly
Invest in Your Deep Sleep for a Healthier Tomorrow
Knowing what percentage of sleep should be deep for a more restorative sleep is essential. Aiming for about 13 to 23 percent of total sleep in the deep sleep allows your body and mind to recharge and repair.
Simple lifestyle adjustments, like sticking to a regular sleep schedule, reducing screen time before bed, and creating a calm environment, can help you achieve deeper, more restorative rest. With consistency and awareness, you can transform your nights into a true source of recovery and wake up ready to take on each new day.