Pain and Sleep

Arthritis, fibromyalgia, and gout keep people awake. Back pain, headaches, menstrual cramps –all sorts of painful maladies leave sufferers less able to fall asleep or stay asleep. Sleep is often a respite from pain but if the discomfort is so strong that the person cannot sleep, the juxtaposition is a special irony.

It’s estimated that 50-80% of chronic pain patients report sleep disturbances. The worst is when pain and sleep loss get into a downward spiral of awfulness, leading to the low quality of life. Pain makes it hard to sleep, poor sleep makes the pain subjectively worse, and both lead to depression, which also affects sleep disorders and pain experience. Cognitive behavioral therapy is a possible solution for both living with pain and alleviating problem sleep.

Pain medication has a profound influence on sleep, even aside from its analgesic effects. Opioids fragment the sleep cycle, even though it may subjectively seem to the patient that the sleep is better, at least in the short run. Over-the-counter pain meds like ibuprofen and aspirin also affect the sleep cycle, although not to the same extent. The effect is not uniformly bad, of course, if the pain medication lets the person get to sleep.

Cause and Effect Runs Both Ways

People with insomnia are more likely to have chronic pain than those without. Experts estimate 25-40% of patients with chronic pain have insomnia(ref), many times the rate among those without.

Does pain make the sleep worse or does poor quality sleep degrade make the pain feel worse? Both. Don’t discount the effect that a good night’s sleep can have on a person’s quality of life and ability to tolerate pain. The subjective intensity of pain decreases when a person is well rested. Hyperalgesia – increased sensitivity to pain – is a result of loss of sleep, especially loss of REM sleep. Which is ironic, because the opiioid drugs used to treat severe pain suppress REM sleep and may make patients more sensitive to the pain they feel. Antidepressant drugs also suppress REM sleep and make us complain about pain more (maybe this is partly the cause of the stereotype of the diva). Poor sleep quality is correlated with more severe pain and increased fatigue.

Rheumatoid arthritis patients complain about sleep problems often and the sleep difficulty and the pain support each other in a viscous cycle.

It's well known there is a connection between pain and mood. And between depression and sleep disorders. Researchers studied arthritis patients using the HAQ-pain scale, the Beck Depression Inventory-II, the Medical Outcomes Study Short Form - 36 vitality scale for fatigue, and the Pittsburgh Sleep Quality Index for sleep quality and disturbances. They found that poor sleep quality was correlated with disability in the arthritis patients.

Scientific article: Sleep Quality and Functional Disability in Patients with Rheumatoid Arthritis

Lower back pain is known to affect sleep, both the quality and sleep latency. The Mayo Clinic website has interesting pictures of sleeping positions that may help reduce back pain.

Recognizing that pain and sleep disorders often go hand-in-hand, the pharmaceutical companies have introduced combination drugs – over-the-counter pills that include both a sleep aid (an antihistamine) and an analgesic. The very popular Tylenol PM is one such product, and there are many others.

The topic of pain and sleep is tied closely to that of aging and sleep. A much higher percentage of seniors experience chronic pain than young and middle-aged adults. A much higher percentage of seniors experience sleep disorders, too.

Pain during REM sleep

People have reported pain during their dreams that isn't real pain – it's dream pain – and vanishes when they awake. More common is real bodily pain that could be felt if the person was awake but which was incorporated into the narrative of the dream. Vivid narrative dreams happen when the brain is in REM sleep and during REM the skeletal muscles are paralyzed. This paralysis may contribute to bodily pain and make it worse than in NREM sleep when the body can more easily move around.

Psychologists did a test where they induced a mild pain in sleepers in the REM stage of sleep. Upon awakening, the subjects often reported dreams (about 30%) that included pain in the same part of the body that the researchers applied pressure to. The subjective level of pain during the dream tended to be higher than the pain when the person was awake. Curiously, burn patients report about the same percentage of pain dreams even though the level of pain they experience is much higher than the subjects in the psychologists' tests.

Noise and Sleep

Loud or unpredictable noises fracture sleepers’ rest, sometimes causing awakening, and sometimes triggering a shift to a different stage of sleep. Noise that disrupts slow-wave sleep leaves people waking feeling unrefreshed and often with diffuse pain and tenderness, even in healthy people.

Individuals have different responses to noise, of course. Researchers have even figured out how to predict who will wake up from noises, based on electroencephalography (EEG) readings.  People who have more sleep spindles on the EEG readings during a normal night of sleep have more tolerance for noise.  In other words, people who have more active brains when asleep tend to sleep better when it is noisy.

White noise – a constant hum in the background at low volumes – can help some people sleep.   Presumably this is because the noise drowns out softer unpredictable sounds.  There are commercial products that generate white noise that some find helpful and others use humidifiers partly because of their constant hum. White noise can induce sleep in infants.

Rain helps improve the subjective quality of sleep for many.  You have probably heard people tell you they slept great because of the rain. This may be due to a combination of the white noise generated during the rain (but not in a thunderstorm), sudden reduction in outdoor temperature, changes in the electrostatic characteristics of the air. Further, the "fresh" air following rain - perception of coolness, sweet smelling air, low particulate account - is conducive to sleep.

Aircraft noise disturbs sleep and when bad enough can result in sleep-deprived behavior during the day. The WHO claims 1 in 3 Europeans suffers health harm from excessive traffic noise (cars, planes, etc.).  20% of Europeans are said to be at risk for significant health damage from nighttime noise. A Korean study found railway traffic was more bothersome and problemetic to sleepers than automobile traffic.

What about birdsong and the natural sounds of morning?  Many find these sounds pleasant when they are relaxed and report they enhance the sleep experiences around dawn when the sleeper is often in REM sleep.

A related issue is the effect of rocking on sleep.  Parents rock babies to sleep and some baby cribs are set to rock.  People enjoy sleeping in hammocks that can rock.  Is there scientific explanation of that?  A Swiss study found the rocking at 0.25 Hz facilitates and transition from stage 1 to stage 2 sleep.  The density shown on EEG reports increases when the sleeper is rocking.

The Sound Sleeper

What does it mean to say someone is a sound sleeper? Or that you slept soundly? One thing it means is that the sleeper does not wake readily from noises. "Resistance to acoustic disturbance" is a measure of the depth of sleep, and it varies over the course of the night. How likely we are to wake up from sleep in response to noise varies throughout the night and even within any given stage of sleep. In deep sleep we are less apt to be awakened from external noise. Spindle activity in light sleep seems to be a measure of how sound (less sensitive to sounds) we are.

 

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