According to the Rechtschaffen & Kales (R & K) Standard of 1968, deep sleep can be described as stage three of non-rapid eye movement sleep and is often referred to as “slow wave sleep”. There’s no clear difference between stages three and four; however, stage three has 20 to 50 percent delta activity while stage four has over 50 percent. Since the year 2008, the American Academy of Sleep Medicine no longer refers to stage four, and stages three and four have combined to create stage three. Therefore, a period of 30 seconds’ sleep, consisting of 20%-or-more slow-wave sleep, is now considered to be stage three. Slow wave sleep (deep sleep) is one of the Stages of Sleep.

What is Deep Sleep? What is Deep Sleep

Deep sleep is the sleep stage that is associated with the slowest brain waves during sleep. Because the EEG activity is synchronized, this period of sleep is known as slow-wave sleep: it produces slow waves with a relatively high amplitude and a frequency of less than 1 Hz. The initial section of the wave is indicated by a down state; an inhibition period whereby the neurons in the neocortex are silent. It’s during this period that the neocortical neurons are able to rest. The next section of the wave is indicated by an upstate; an excitation period whereby the neurons fire briefly at a rapid rate. This state is a depolarizing phase, whereas the former state is a hyperpolarizing phase. In contrast with Rapid Eye Movement sleep, the main characteristics of slow-wave sleep are absent or slow eye movement, moderate muscle tone, and lack of genital activity.

Features of Deep Sleep

  • EEG demonstrates delta waves (high amplitude, low frequency)
  • Consolidation of memories
  • High arousal threshold
  • Presumed restoration of body and brain

Why Is Deep Sleep Important?

Why is deep sleep importantDeep sleep is important for the consolidation of new memories, and is often referred to as “sleep-dependent memory processing”. Thus, individuals with primary insomnia will have impaired memory consolidation and won’t perform as efficiently as normal patients when completing memory tasks following a period of sleep. In addition, declarative memory is improved with slow-wave sleep, and this includes both semantic and episodic memory.

A central model has been created on the assumption that long-term memory storage is promoted by interaction between the hippocampal and neocortical networks. Several studies have shown that, once subjects have been trained to learn a declarative memory task, there was a significantly higher density of human sleep spindles when compared to the non-learning control task. This occurs due to unconscious wave oscillations that make up the intracellular recordings from cortical and thalamic neurons.

Function of Deep Sleep

Human sleep deprivation studies seem to suggest that the principal function of deep sleep may be to give the brain time to restore itself from its daily activeness. An increase of glucose metabolism in the brain occurs as a result of tasks that require mental activity. Yet another function affected by slow-wave sleep is growth hormone secretion, which is always greatest at this stage; plus, it also creates both an increase in parasympathetic neural activity and a decrease in sympathetic neural activity.Function of deep sleep

In deep sleep, the highest arousal thresholds are observed; such as the difficulty of awakening by the sound of a particular volume. When a person awakens from slow-wave sleep, they’ll generally feel quite groggy, and cognitive tests after awakening do indicate that mental performance can be impaired for periods of up to 30 minutes when compared to awakenings from other stages. This phenomenon is known as “sleep inertia”.

There’s always a sharp rebound of slow-wave sleep after sleep deprivation, meaning that the next bout of sleep will not only include more slow-wave sleep than normal, but deeper slow-wave sleep. The previous duration of this stage, in addition to the duration of prior wakefulness, will determine the duration of slow-wave sleep. When determining the amount of slow-wave sleep in any given sleep period, the major factor to note is the duration of preceding wakefulness, which is typically related to the build-up of sleep-inducing substances in the brain.

Sleep Disorders During Deep Sleep

There are several sleep disorders and parasomnias that occur predominantly during slow wave sleep. Sleepwalking (somnambulism), night terrors (sleep terrors), bed-wetting (enuresis), sexsomnia, and sleep eating are all associated with slow wave sleep. Individuals with narcolepsy often have fragmented deep sleep.

Factors that Increase Slow-Wave Deep Sleep

Factors that have shown to increase slow-wave sleep in the sleep period that follows them include intense prolonged exercise and body heating, such as immersion in a sauna or hot tub. Factors that Increase Slow-Wave Deep SleepIt’s been shown in studies that slow-wave sleep is facilitated when brain temperature exceeds a certain threshold, and it’s believed that circadian rhythm and homeostatic processes regulate this threshold. An unusually low carbohydrate diet consumed over the short term in healthy sleepers promotes an increase in the percentage of slow-wave sleep, including a production in the percentage of dreaming sleep (REM sleep), when compared to the control with a mixed diet. It’s believed that these sleep changes could well be linked to the metabolism of the fat content of the low carbohydrate diet. In addition, the ingestion of antidepressants and certain SSRI’s can increase the duration of slow-wave sleep periods; however, the effects of THC on slow-wave sleep remains controversial. Total sleep time in these instances is often unaffected due to a person’s alarm clock, circadian rhythms, or early morning obligations.

How to Get More Deep SleepHow to get more deep sleep

The most important thing that you can do to increase your amount of deep sleep is to allow yourself adequate total sleep time. Often, individuals will deprive themselves of adequate total sleep. In addition to reducing deep sleep, REM sleep is also shortened.

There is some data to suggest that vigorous exercise can increase or consolidate deep sleep. Some sleep specialists recommend aerobic activities like jogging, running, and swimming. For those who are prone to insomnia, it is best to exercise earlier in the day and not before bedtime.

26 thoughts on “Deep Sleep: How to Get More of it

  1. JJ Reply

    I have been researching deep sleep because lately I have been exhausted, red-eyed, and foggy despite the amount of time I spend asleep. About three weeks ago I invested in a Galaxy smartwatch and while averaging 7-7.5 hours of time sleeping I consistently get 0-7% deep sleep. This is curious because I am only 38 and I thought it only decreased significantly for 60+ folks. I have no issues falling or staying asleep and am fit, regular weight, and I don’t do anything of those things that would hinder my deep sleep. I believe I have good sleep hygiene. I considered that it might be my new smartwatch so I checked my last Fitbit from a year ago and it wasn’t much better then. Is it more likely that the exhaustion is from stress rather than deep sleep? I’m trying to figure out if there anything I should be doing to fix this.

    • Elysabeth Reply

      I have the same issue – there are just too many nights after which I wake up in the morning feeling like I slept about 5 min – even if it was 8 hrs. I constantly felt tired. After a sleep study, I was told that I wasn’t getting almost any deep sleep, a condition considered a form of insomnia. Would like to learn more about how to get the deep sleep I need.

  2. Deb Reply

    Hey Melly,
    I have spent my life being hypersomnic. Coffee is helpful, but I am wondering if espresso might be better. I usually only have a couple cups in the morning (I get up between 5 & 6). I don’t have any caffeine after 2:30 or so. Some of the other comments were interesting. I might give the elimination of carbs after a certain amount of time.

  3. Marlene Reply

    The Oura ring is the best sleep tracker I have seen. Safe (it has an “airplane mode” so no EMFs on your body). It is amazing for tracking so much more find a discount code and it is $250. Well worth the money

  4. Phil Chenevert Reply

    My Fitbit (Charge 2) is amazing. I just discovered how much information it can generate each night and am using that to plot my total sleep time, sleep efficiency (time in bed/time asleep), REM, Light and Deep sleep as well as awake amount. I have sleep Apnea and use a CPAP. By moving my bed time to an earlier hour from midnight, using f.lux app to eliminate blue light from my computer screen and removing night lights from my bedroom, my Deep sleep periods have gone up 45%. I’m 78 years old and feeling much better now.

    Now if I can juust talk the CPAP makers into building sleep monitoring into the machine and letting me get at it, that would be great.

  5. Kenneth P Reply

    My thoughts on deep sleep are based on a book I recently read, “The End Of Alzheimer’s,” by Dale Bredesen, M.D. I don’t think it’s a coincidence that seniors like me typically begin having problems with sleep in general and with getting sufficient deep sleep in particular. Dr. Bredesen notes that during deep sleep, our brains engage in chemical cleansing of substances (including amyloids) that block communication between synapses in the brain.
    One way to increase deep sleep is to avoid eating just before going to bed; ideally, several hours before. (The theory is that if you put food in your gut just before going to sleep, your body sends too much of its blood supply to the gut for digestion to have a sufficient supply for deep sleep cleansing of the brain. Makes sense to me.)
    I try to consume zero calories after 8 pm.
    More to the point: I’ve started fasting through one dinnertime per week; that is, one day a week, no solid food after lunch.
    I’m six weeks in. My FitBit watch just told me I had 70 minutes of deep sleep last night. Previously, I wasn’t getting more than 30 minutes (out of the same period, approximately seven hours, of sleep per night).
    I’ll keep on checking (and I know a watch is not scientifically calibrated, but still…).
    Would be interested if others have a similar experience.

  6. Melly Reply

    And one thing that was not addressed in this article is hypersonia. Those of us that suffer with hypersomnia feel tired and groggy all day, every day no matter how much sleep we get. It feels like you’re sleeping you’re life away and it’s miserable. Do you have any suggestions on how to deal with it

  7. Sergio Gutierrez Reply

    I have a Garmin watch to record the sleep time, last night the numbers was as following:

    Deep 1h 30m
    Light 4h 20m
    Rem 1h 10m

    Are deep sleep enough? It is not, how can I increase?

    Thanks in advance


  8. Aluna Reply

    Cheryl you may want to check to see if you have sleep apnea. And Gregg thanks for the advice I will try it, no carbs past 1. No food 2 hrs before sleep.

  9. Anonymous Reply

    I was not able to properly sleep during 40 years then decided to go with the a couple of neurologist and the don’t found anything worn in my brain. I started to reduce my weigh but was not able to reduce a lot reducing fat, after seeing them documentary of fed up I discovery that sugar is worst than anything else so I stop eating sugar as much as possible, after three months by the first time in my life I star sleeping better my wife steel eat a lot of sugar and she is able to sleep good and right a away. I am coming here due I was looking s way to increase my deep sleep but probably I am not to bad now. leaving as much as I can sugar and exercise regularly was the best decision in my life.

  10. Cheryl Reply

    I’ve got a sleep tracker and I am low in deep sleep, am on a diet so its not that as its low sugar, low fat.. I don’t eat after 7 pm.. I exercise loads Inc cycling and walk an avg 12500 steps a day.. I will either crochet or watch TV before bed so I’m never on the net.. I have tried listening to music.. Not crocheting, laying in bed with lights off hours before bed.. Going late, going early, and I cannot get it right.. I am starting to feel exhausted constantly.. I don’t get it at all.. Any suggestions? Am trying a bath and essential oils tonight.. To see if that helps and a bedtime app for my little one.

    • Christina Reply

      Hi Cheryl, The article mentioned deep sleep being associated with the brain’s metabolism of fat. Do you think you may need more healthy fat vs low fat?

  11. Audie Reply

    Is it possible to have too much slow wave sleep? And what is the result if you do?

    • Alfy Reply

      You cant get more deep sleep than what you need. It’s not like a drug or something where you can overdose. You get what your body needs

      • Jmat Reply

        You dont know what your talking about. Deep sleep varies for many reasons and a lot of people suffer a lack of that stage of sleep which affects them in many ways.
        New studies suggest stress, diet and other factors contribute to the amount if time spent in each stage if sleep. Research and experience suggests you have a big mouth and little brain.

    • Marca Reply

      How do you know the sleep tracker is accurate? I’ve heard they aren’t which is why I would hesitate to buy one.

  12. greg Reply

    I went from 0 to 15 mins of deep sleep for about 1 year to over 1 hour for the last three weeks by not eating before bed (2 hrs.) and no carbs past 1 o’clock pm. I feel more awake sharper with less sleep. I’m a little pissed I’ve read this in only one book and found nothing about laying off carbs at night on any site. I also started eating in a 12 -8 pm window and fall asleep at 10 of all these changes think it was mostly laying off the carbs after my noon meal that increased my deep sleep. (used a sleep tracker )

    • Kathleen Reply

      Hey, greg. When you say “lay off carbs” what are you talking about? Almost everything has carbs. Are you only eating meat? I’m trying to increase my deep sleep time and just received a fitbit tracker and the only night that I reached the “benchmarker” for deep sleep was after a meal with steak. No potato just salad with that. Just trying to figure out how to increase my deep sleep.

    • Becky Reply

      I’m beginning to wonder about the effects of carbs on my sleep or lack thereof and think it is certainly worth a try. Can you tell me the book that you read this in? Perhaps they have some more useful tips to try.

  13. Carl M Reply

    “ In addition, the ingestion of antidepressants and certain SSRI’s can increase the duration of slow-wave sleep periods; however, the effects of THC on slow-wave sleep remains controversial”
    I had to look up THC —amazing is there a medical study anywhere that shows this increases slow-wave sleep. Is it controversial because it is a Federally illegal drug or because there are no reliable studies to back up the inference?
    Poorly written —SSRI’s are a antidepressant. The statement above would lead some to think that antidepressants and SSRIs are 2 different medications. Excluding SSRIs not all antidepressant increase deep wave sleep in fact Please SHOW ME A LIST OF ANTIDEPRSSANT THAT INCREASE DEEP WAVE SLEEP!

    • John Reply

      Not all antidepressants are SSRIs, sometimes they are two different medications.

  14. Carl M Reply

    “Why Is Slow-Wave Sleep So Important?”
    Ok so how do I find a sleep medicine doctor that will pay attention to this?
    All they want to do is tell me my CPAP readings are fine while my sleep studies always comment on how little slow-wave sleep I have.
    Where is the research and the emphasis to find a reliable way to monitor sleep stages at home?

      • Diana Sowell Reply

        THC is a schedule 1 drug marinol is manufactured from big pharma. Not the same thing.

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