Restorative sleep is defined as sleep which lasts a recommended amount of time, in which a person has gone through all stages of sleep, followed by a feeling of refreshment, clear-mind, and physical restfulness upon waking up.
Opposite to restorative sleep is non-restorative sleep, which doesn’t provide us with a feeling of refreshment. Non-restorative sleep is frequently described as the ‘subjective experience’ that the sleep hasn’t been good enough. It usually comes after short sleep hours, but sometimes even after 8 hours of sleep, we may still be drowsy and tired all the time. This means that sleep quality is impaired – and what seems to impair it is a variety of factors, including age, gender, lifestyle habits and a number of sleep disorders (primarily insomnia, fibromyalgia, and Chronic Fatigue Syndrome).
Although there are some ways to reach good, refreshing sleep again, there is no single solution which could help everyone. Non-restorative sleep (NRS) has frequently been identified as a symptom of insomnia and, although it can be so, scientists have found that even otherwise healthy individuals may experience NRS.
Non-restorative sleep is followed by problems like pain, impairment of judgment and learning, fatigue, and frequent wakings from non-REM sleep (which can be observed by EEG – electroencephalogram) readings.
Many studies have been dedicated to the relation between NRS and other sleep disorders, but recently there has been a growing interest in NRS not being a sleep disorder symptom.
What are the symptoms of non-restorative sleep?
Some of the main telltale signs that you didn’t get restorative sleep are:
- Fatigue, low energy levels during the day,
- Excessive Daytime Sleepiness,
- The feeling of tiredness upon waking up,
- Irritability, depression, panic attacks,
- Low immune system, frequently having a sore throat, cold, or other health issues,
- Inability to concentrate and perform daily tasks efficiently, memory problems,
- Pain in various parts of the body,
- Having trouble falling asleep and/or staying asleep.
Two researchers from Toronto, Canada have developed a Nonrestorative Sleep Scale (NRSS), which is a subjective sleep quality questionnaire which consists of 34 questions. In order to find out whether they have a problem with sleep quality, people answer questions about how they feel after sleep, what their cognitive abilities and energy levels during the day are and many more. It was concluded that NRSS provides trustworthy results and that the scale is an excellent tool in determining the presence of NRS.
Which disorders cause or are caused by non-restorative sleep?
NRS can be linked to a number of sleep-related and unrelated disorders, mainly those that disrupt the length of sleep and/or the quality of sleep.
Insomnia is frequently linked to NRS because these people usually have problems with falling asleep and staying asleep. About 30-40% of people with difficulty falling asleep (DIS) and difficulty maintaining sleep (DMS) also experience daytime symptoms of NRS.
Gastroesophagial reflux disease (GERD) leads to poor sleep, as nocturnal heartburn prevents people from sleeping sufficiently. Those who suffer from GERD experience frequent awakenings, most likely due to the feeling of ‘burning’.
Restless leg syndrome (RLS). Those who suffer from RLS have an urge to move their legs. Especially during the night, after a period of restfulness, they feel an unpleasant sensation or even pain in their legs. This need negatively impacts their nighttime sleep quality and quantity.
Obstructive sleep apnea (OSA). Also spelled as sleep apnoea, it appears in 2% of the female and 4% of the male population. It is a sleep breathing disorder which happens after the airway is blocked and breathing stops. Sufferers from OSA wake up frequently during the night, although the following day they may not be aware of what happened.
Fibromyalgia syndrome (FMS) is a condition which causes people to feel severe widespread pain throughout their body, interrupting their sleep and daytime activities. Symptoms of FM may gradually increase over time or appear after significant trauma, surgery, or stress. Chronic pain prevents a person from reaching deeper sleep stages.
Chronic fatigue syndrome (CFS) is tightly correlated with NRS, as its symptoms are almost identical – extreme exhaustion, loss of memory, pain, but also enlarged nodes in the neck and armpits. People with CFS still feel exhaustion even after 24 hours has passed from the time of their mental or physical exercise.
Nocturia or overactive bladder (OAB) affects the sleep by fragmenting it with frequent nightly awakenings. The strong urge to urinate often disrupts the cycles of sleep and leaves you with a lack of a good night’s sleep.
Apart from these disorders, there are some more factors causing non-restorative sleep. For example, various brain injuries/head traumas can result in the disruption in the sleep-wake cycle and other processes which occur in the body.
What are the consequences of NRS?
The following picture shows the amount of deep sleep and REM sleep insomniacs with NRS have compared to those with NRS-only and healthy individuals. The results were recorded using polysomnography during each hour of sleep.
|Figure 1 Time spent in stage 3/4 sleep (A) or REM sleep (B) over the 8-hour polysomnography period (mean for each hour on Days 9/10). PSG, polysomnography |
From: Nonrestorative Sleep as a Distinct Component of Insomnia. Sleep. 2010;33(4):449-458. doi:10.1093/sleep/33.4.449
This graph can help us realize that people with NRS are suffering from sleep deprivation. Even though they had the same amount of sleep time as healthy volunteers, they simply didn’t get the much-needed slow wave sleep and REM sleep. (Please note that in picture A it is referred to the stages 3 and 4, but according to the new sleep stage division, they are merged into one stage – stage 3.)
Together, these two sleep stages ensure our immunity is strong, our tissues are repaired with the help of the human growth hormone, our memory is consolidated, amygdala (fear and emotion center in the brain) is rested and the “feel-good” neurotransmitters are replenished, the brain is cleared from the plaque which causes Alzheimer’s disease. All of this and much more is what helps us feel refreshed and rested.
Sufferers of NRS lack these benefits. They can experience all of the symptoms associated with sleep deprivation, such as circadian rhythm disorders, weight problems, migraines, anxiety, bad memory, poor learning abilities, higher risk of illnesses and serious diseases.
Excessive chronic fatigue can disrupt the activity of the flip-flop switch in our brain, which regulates falling asleep and waking up. Sleep paralysis is one of the disorders connected with REM and flip-flop switch irregularities. It happens after a person wakes up from a REM stage, but even though partially or fully conscious, is still unable to move. This waking may be followed by vivid hallucinations and a subjective feeling of inability to breathe, which makes this disorder unpleasant.
Another example is having hypnagogic hallucinations. They are strong dream-like sensations which occur just before sleep. For example, as a person drifts off into sleep, they may have a strong feeling that someone is in the room or that they can hear or smell something.
Excessive tiredness can be followed by falling asleep any time during the day, even involuntarily and in inappropriate moments. This is known as narcolepsy and it can be accompanied by hallucinations just before getting right into REM stage upon falling asleep.
Cataplexy is quite an unusual disorder – it employs the REM atonia (muscle paralysis) after a person experiences strong positive emotions. It may happen that a person becomes paralyzed after laughing out loud.
Although it somewhat frequently happens in children, they usually grow out of sleepwalking. However, in adults, it can be a sign of sleep deprivation.
These disorders are rarely documented in healthy, well-rested individuals.
How to alleviate the consequences of non-restorative sleep and regain healthy sleep?
There are many conventional tips for improving your sleep. Here are some:
- Avoid caffeine in drinks and food, because not only does it keep you awake, it also disrupts your natural dopamine levels and circadian rhythm.
- Don’t drink alcohol because it prevents you from reaching deeper stages of sleep.
- Maintain a regular sleep-wake cycle – always go to bed and get up at about the same time.
- Prepare for sleep mentally. If you have things to do the next day, think about them before bed. Read a book (not an e-book, screen lights may inhibit melatonin production and make you less sleepy) and relax just before sleeping.
- Sleep in a cool, dark room. Colder termperatures increase calorie consumption and can help you lose weight as well as have a good night’s sleep.
- Make sure your room is quiet. If you can’t get rid of the noise in your apartment, consider getting earplugs.
- Shut down electronics at least two hours before bed.
- Exercise at least 30 minutes every day. Exercise has been proven to improve sleep quality, reduce stress, and strengthen overall health.
- Don’t eat high-calorie food before bed. You can have a light dinner about 2 hours before bed but refrain from big meals as they will keep you awake.
You can also opt for certain foods and food supplements to help you sleep better.
- Melatonin (a neurotransmitter which makes us sleepy). Eat grains, nuts, and seeds, corn, asparagus, olives, and grapes to get melatonin naturally.
- GABA (Gamma-Aminobutyric Acid) is also a natural neurotransmitter you can take for better sleep. GABA is responsible for relieving stress, relaxation, and good sleep. The best natural source of GABA is fermented food like kefir and kimchi.
- Drinks like warm milk and chamomile, valerian, and peppermint tea can help in relaxation and help you sleep well.
- Magnesium can be found in green vegetables, leafy greens, nuts, beans, legumes, seeds, and whole grains.
Although found in nature, these substances are also sold in drugstores as food supplements. There are many more foods that can work as sleep aids, but a balanced diet should cover all your vitamin and mineral needs.
There are some newly implemented therapies which can improve your sleep, like using a CES (Cranial Electrotherapy Stimulation) device. FDA has approved CES for treating sleep problems and mood disorders like anxiety and depression.
One thing you should know is that deep sleep is also known as restorative sleep because of its restorative benefits. You might want to learn more about how to increase deep sleep.
Who is at the greatest risk of having non-restorative sleep?
Many studies offer an answer to this question but they all agree on the following – young females of low socioeconomic status and education level, alcohol, drug, and nicotine users with depression and/or other psychological problems are mostly affected. Those with nocturia, GERD and other sleep-related disorders were at high risk as well. Some of those studies are described in the paragraphs below.
A study in Japan
A Japanese study conducted on as many as 9,788 residents of Nahagama City, aged between 30 and 74 has reached certain conclusions which can give us an insight into which group is at the highest risk of developing NRS.
Men were in a more favorable position to women with 42% NRS sufferers, while half of the examined women had NRS. Further, the researchers concluded that NRS symptoms declined with age, affecting mostly the younger population. Why this condition is related to young study participants may be explained by the fact that they are more likely to indulge in unfavorable behavior. This unfavorable behavior consists of hypnotic drug use, poor sleep habits, and sedentary lifestyle. Moreover, depression, nocturia, and GERD were found in those suffering from non-restorative sleep. Interestingly enough, the researchers underline that unfavorable eating habits were not related to this problem.
A study in Europe
This clinical study raised the question of nationality in relation to NRS. It has also found that 10% more women experienced NRS than men and that it affected a younger population mostly with depression or other psychological disorders. However, they found that the United Kingdom and Germany had the highest percentage of NRS sufferers out of the whole population, while Spain, Portugal and the South of Italy had the lowest. It could mean that the climate plays a role in the length of sleep.
A study in the United States
A sleep study conducted throughout the United States showed that poorer females were likely to develop nocturnal insomnia symptoms (NIS) as well as NRS. What this study also included was the presence of inflammation in those who had sleep problems. They measured the level of C-reactive protein (CRP) in 9,830 participants and found the following.
Figure 2 Comparison of mean C-reactive protein levels (mg/dL) across groups.
From: Differentiating Nonrestorative Sleep from Nocturnal Insomnia Symptoms: Demographic, Clinical, Inflammatory, and Functional Correlates. Sleep. 2013 May 1; 36(5): 671–679.
Model 1 in this figure is adjusted for the following: age, sex, poverty income ratio, ethnicity, educational level, and marital status.
Model 2 is adjusted for the same factors as Model 1 with the addition of Patient Health Questionnaire (PHQ-9) total score, body mass index, sleep duration, any cardiovascular disease, arthritis, lifetime smoking, clinician-diagnosed sleep apnea, habitual sleeping pill use, habitual snoring, and restless legs syndrome.
Figure 2 shows us that having NRS only is linked with an increase in inflammation, however, if NRS is accompanied by insomnia, C-reactive protein has a significantly higher presence.
The same study has found that NRS-only occurs mostly in non-Hispanic whites, whereas insomnia with and without NRS was the highest in Hispanics.
Mind your sleep
Ensuring quality sleep plays an important role in our mental and physical health throughout our lives. Good sleep is especially essential for children and teenagers – research shows that being sleep deprived early in life later leads to bad sleeping habits and poor health choices in adults. This means that a considerable percentage of people who have problems with NRS, insomnia, circadian rhythm, or other mentioned disorders was likely not getting enough good sleep as a child.
Chronic fatigue is a serious and dangerous matter as it can lead to work-related injuries and injuries of other people (especially for those who work in factories or as drivers).
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