We all know that sleep plays a crucial role in our overall health and well-being. But did you know that the quality of your sleep is just as important as the quantity? In fact, there are different stages of sleep, and how much time you spend in each stage can greatly impact the restorative benefits of your sleep. In this comprehensive guide, we will dive deep into the topic of deep sleep and uncover the secrets of how much deep sleep you really need for optimal health and vitality.
Why We Need Deep Sleep
Deep sleep, also known as slow-wave sleep, is the third stage of non-rapid eye movement (NREM) sleep. During this stage, your body undergoes essential processes that are vital for your physical and mental well-being. Deep sleep is responsible for repairing and restoring your body, boosting your immune system, consolidating memories, and promoting muscle growth. It is during this stage that your brain waves appear in long, slow waves called delta waves, with a frequency of 0.5 to 2 Hertz [1].
Not getting enough deep sleep can have serious consequences on your health. Studies have shown that inadequate deep sleep can lead to learning difficulties, decreased cognitive functioning, increased susceptibility to infections, and a higher risk of long-term health concerns [2]. It is crucial to understand the stages of sleep and how much deep sleep you should aim for to ensure you reap the full benefits of a good night's rest.
The Stages of Sleep
Sleep occurs in cycles, and each cycle consists of different stages. The two main types of sleep are rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep. NREM sleep is further divided into three stages: N1, N2, and N3 [3]. Let's take a closer look at each stage:
Stage 1: Light Sleep
The first stage of sleep, also known as N1, is the transition from wakefulness to sleep. It is a relatively short stage, lasting around one to seven minutes. During this stage, your body starts to relax, and brain and body activity begin to slow down. You may still have some awareness of your surroundings, and you can be easily awakened [4]
While there is no specific recommended minimum for light sleep, spending excessive time in this phase may indicate a lack of restful sleep in the deeper stages. It is important to strive for a balanced distribution of sleep across all stages to ensure optimal rest and rejuvenation.
Stage 2: Core Sleep
Stage 2, also known as N2, is considered a deeper form of sleep compared to N1. Your breathing, heartbeat, and brain activity continue to slow down, and your muscles relax even further. This stage is characterized by short bursts of brain activity that help resist being awakened by external stimuli [5].
Stage 2 sleep, often referred to as "core" sleep, typically lasts for about 10 to 25 minutes in the first cycle and becomes longer with subsequent cycles throughout the night. On average, approximately half of your total sleep time is spent in this stage [4,6]. Although there is no specific recommended minimum for sleep in this stage, it is essential for maintaining a healthy sleep pattern.
Stages 3 and 4: Deep Sleep
Stages 3 and 4, collectively known as deep sleep, are the most restorative stages of sleep. In these stages, your breathing, heartbeat, body temperature, and brain waves reach their lowest levels. Your muscles are extremely relaxed, and it is difficult to wake someone who is in these stages [7].
Deep sleep is the time when your body undergoes crucial repair and restoration processes. Tissue growth and repair occur, important hormones are released and in the case of the stress hormone cortisol, purged, memories are consolidated, the immune system is strengthened, and the brain detoxifies [8]. It is during deep sleep that you experience the most restorative benefits of sleep.
Ideally, you should aim for approximately 13 to 23 percent of your sleep time to be spent in stages 3 and 4 [9]. For example, if you get 8 hours of sleep, you should aim for about 1 to 2 hours of deep sleep. However, it is important to note that the timing of your sleep can significantly influence the amount of deep sleep you get. Research suggests that sleeping between the hours of 8 p.m. and midnight increases the likelihood of experiencing restorative deep sleep, regardless of your waking time [10].
REM Sleep
REM sleep is the final stage of the sleep cycle and stands for rapid eye movement sleep. It is characterized by increased brain activity resembling wakefulness, while the body experiences temporary muscle paralysis. This stage is closely associated with vivid dreaming and plays a crucial role in cognitive functions such as memory, learning, and creativity [11].
Your first REM cycle typically begins about 90 minutes after falling asleep and recurs every 90 minutes throughout the night. While the first REM stage may last only a few minutes, later stages can extend up to an hour. In total, you should aim for approximately 20-25% of your sleep time to be spent in REM sleep [12]. REM sleep tends to dominate the latter half of your sleep, becoming longer as you continue to snooze.
How Much Deep Sleep do I Need By Age?
There is currently no official guideline on this, but you do generally get less deep and REM sleep as you get older and you should in theory need less as this element of sleep is part of your growth cycle.
Remember that you spend only 25% of the night in deep sleep, so from 8 hours sleep you’d get about 2 hours deep sleep. More if you’re younger, due to the nature of your sleep wake cycle.
As a result, it can be a bit difficult to break it down ideally however, there are several things that should be considered, but as a rule of infants need the most, followed by children, teens, adults and the elderly. There are some blips with teenage years, where they may require more than when they were younger, due to growth and emotional changes. In these cases teenagers can need up to 3 hours of deep sleep, [13] it can be very confusing for parents wondering why their child looks like an adult, but wants to sleep half of the day.
Rough Guidelines For How Much Deep Sleep Do You Need By Age
Ages 0-2 years: Whilst deep sleep isn’t calculated very well for infants, sleep time required starts at 16 hours declining to 13 by age 2.
Ages 2 – 13 years: Again, we have the same issue calculating deep sleep, but it starts around 13 hours, declines to 11.5 by 5 years old and lowers to about 10.5 hours through childhood. But, the exact times are different based on different recommendations.
Ages 13 – 19: 2-3 hours of deep sleep or 9-12 hours overall sleep, this generally declines with age, but growth and other hormonal stresses can increase this need.
Ages 20 – 55: 2 hours of deep sleep or 6-8 hours
Ages 55+: ideally 2 hours of deep sleep, but it’s less essential as long as it’s not happening every night, broken sleep is not always an issue. Or 6 hours of normal sleep. [14]
Factors Affecting Sleep Stages
Several factors can influence the different stages of sleep and the amount of deep sleep you get. Let's explore some of these factors:
Age
The amount of time spent in each sleep stage varies significantly throughout a person's life. Newborns, for example, tend to have the most REM sleep, with REM stages occurring as soon as they fall asleep. On the other hand, older adults generally require less REM sleep compared to adults, children, and babies [15].
Recent Sleep Patterns
Your recent sleep patterns, including oversleeping, insufficient sleep, or irregular sleep schedules, can disrupt the normal sleep cycle and make it challenging to return to a healthy sleep pattern. Consistency is key when it comes to promoting optimal sleep across all stages.
Alcohol
Alcohol and certain medications can affect the different sleep stages. While alcohol may initially decrease REM sleep, it can lead to a rebound effect later in the night, resulting in prolonged REM stages. It is important to be mindful of the impact of alcohol and medication on your sleep quality [16].
Sleep Disorders
Sleep disorders such as sleep apnea and restless legs syndrome (RLS) can interrupt the normal sleep cycle and reduce the amount of restful sleep obtained. These conditions may require medical intervention to promote healthy sleep patterns and improve overall well-being.
Achieving a Good Night's Sleep
Now that we understand the importance of deep sleep and the factors that affect sleep stages, let's explore some tips for achieving a good night's sleep:
Establish a Consistent Bedtime Routine
Creating a consistent bedtime routine signals to your body that it's time to wind down and prepare for sleep.
Make Sure to Keep a Good Temperature Balance or Try Sleeping Naked
It's been shown that sleeping naked can allow your body to regulate it's temperature more effectively improving sleep quality. If you don't like having to wash your sheets more often however, you should make sure to wear breathable loose clothing that is made of a natural fabric.
Create a Sleep-Friendly Environment
Make your bedroom a haven for sleep by ensuring it is cool, dark, and quiet. Use blackout curtains or an eye mask to block out any unwanted light, this can be especially important during longer days further away from the equator, as low light tells your body it's time to produce melatonin, the sleep hormone. You can also consider using earplugs or a white noise machine to drown out any potential disruptions.
Limit Exposure to Electronic Devices
The blue light emitted by electronic devices such as smartphones, tablets, and computers can interfere with your body's natural sleep-wake cycle. Avoid using these devices for at least 30 minutes before bedtime to allow your brain to transition into a sleep-ready state.
Engage in Regular Exercise
Regular physical activity is beneficial for overall health, including sleep quality. However, it is important to time your exercise sessions appropriately. Avoid exercising within 2-3 hours before bedtime, as it can increase heart rate and hormone levels that may interfere with sleep initiation.
Practice Stress Reduction Techniques
High levels of stress and anxiety can significantly impact your sleep quality. Incorporate stress reduction techniques into your daily routine, such as meditation, deep breathing exercises, or journaling, to promote relaxation and prepare your mind for restful sleep.
Limit Caffeine and Alcohol Intake
Caffeine is a stimulant that can interfere with your ability to fall asleep and stay asleep. Avoid consuming caffeine-containing beverages or foods within a few hours of bedtime. Similarly, while alcohol may initially induce drowsiness, it can disrupt the normal sleep cycle and lead to fragmented sleep patterns.
Maintain a Healthy Lifestyle
A healthy lifestyle, including a balanced diet and regular exercise, can contribute to improved sleep quality. Focus on consuming nutritious foods, staying hydrated, and incorporating physical activity into your daily routine. These habits promote overall well-being and can positively influence your sleep patterns.
How Much Deep Sleep Do You Need? Conclusion
In conclusion, deep sleep plays a crucial role in maintaining optimal health and well-being. Understanding the different stages of sleep and how much deep sleep you should aim for can help you achieve a more restful and rejuvenating sleep experience. By creating a sleep-friendly environment, adopting healthy sleep habits, and addressing any underlying sleep disorders, you can enhance the quality of your sleep and wake up feeling refreshed and revitalized. Prioritize your sleep, and reap the countless benefits it offers for both your mind and body.
References
1 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6165862/
2 - https://www.ncbi.nlm.nih.gov/books/NBK19961/
3 - https://www.nhlbi.nih.gov/health/sleep/stages-of-sleep
4 - https://www.ncbi.nlm.nih.gov/books/NBK526132/
5 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2365910/
6 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4246141/
7 - https://www.ninds.nih.gov/health-information/public-education/brain-basics/brain-basics-understanding-sleep
8 - https://pubmed.ncbi.nlm.nih.gov/35779511/
9 - https://www.nhlbi.nih.gov/health/sleep/stages-of-sleep
10 - https://pubmed.ncbi.nlm.nih.gov/9628110/
11 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2700890/
12 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4246141/
13 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2528821/
14 - https://order.nia.nih.gov/sites/default/files/2020-12/sleep-and-older-adults-booklet.pdf
15 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5841578/
16 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4666864/
