A new study, the results of which are published in the journal Neuroscience, found that sleep deprivation increases sensitivity to pain due to the special response of the brain to the receptor signal. According to these data, sleep can be a key point in removing chronic pain.
Effects of sleep deprivation
Waking without a sufficient amount of proper rest has a variety of negative effects on the brain: from the onset of a state like intoxication and the disruption of the functioning of memory mechanisms to the restriction of the ability to concentrate and perceive information.
A new study found another neurological effect that had not been previously distinguished – an increased sensitivity to pain, since lack of sleep disrupts the natural patterns of the brain to relieve these sensations.
The urgency of the problem
The discovery made it possible to pay special attention to such common physiological disorders as lack of sleep, chronic pain syndrome and dependence on potent drugs (mostly opioids).
According to current statistics, in the United States alone, about 50,000,000 adults (over 20% of the total population) live constantly in pain, and about 130 people die every day from overdose of symptom-relieving drugs. Similar problems are encountered in many countries of the world.
It was the urgency of the issue that led Matthew Walker and Dr. Adam Krause, a professor of neuroscience and psychology at the University of California, Berkeley, to conduct a joint study on this topic.
How does this happen
For the experiment, a group of 24 healthy young volunteers was recruited. Walker and Krause caused a painful effect by applying heated elements to their legs. In parallel with this effect, scientists scanned the subjects’ brains, examining the mechanisms for processing the corresponding negative sensations.
At the beginning of the experiment, the members of the examined group had no problems with sleep or pain-related disorders. At the first stage, participants were allowed to sleep well at night, and after that, they set and fixed a pain threshold for each, applying elevated levels of heat to their skin and scanning the brain using an MRI machine.
As soon as the threshold of pain sensitivity was determined, the procedure was repeated after a sleepless night.
The results of the experiment and their assessment by scientists
In the second case, all members of the examined group experienced discomfort at lower temperatures, which indicates that their own sensitivity to pain increased after inadequate sleep.
The level of real body tissue injury remains the same, the difference lies only in how the brain assesses pain without adequate quantity and quality of sleep.
The researchers found that the somatosensory cortex of the brain, an area associated with pain sensitivity, was hyperactive when participants were unable to sleep. This confirmed the hypothesis that sleep deprivation would interfere with the functioning of anesthetic neural circuits.
However, it was not without surprises – the unexpected discovery was a decrease after a sleepless night of activity in the adjacent nucleus of the brain, releasing the hormone neurotransmitter dopamine, which increases pleasure and relieves pain. It follows from this that the loss of sleep not only increases the pain in the brain, but also blocks the centers of natural analgesia.
Finally, the researchers found that the brain area, which assesses pain signals and prepares the body for a similar effect, also proved ineffective after a sleepless night.
To confirm their findings, the researchers conducted a survey of more than 230 adults registered on Amazon’s Mechanical Turk online market. Participants reported on their sleep patterns and pain sensitivity levels for several days. Scientists have discovered that even very minor changes at night, reductions that many do not even think about in terms of health effects, clearly affect the intensity of the next day’s pain.
The optimistic conclusion here is that sleep is a natural analgesic that can help cope with pain, reduce it. And yet, ironically, one of the most unfavorable places to sleep is the room where people experience the greatest physical suffering – the noisy hospital ward.
The results obtained during the experiment show that patient care will be noticeably improved, and hospital beds will be released more quickly if health workers seriously take continuous sleep as an integral component of successful and soonest healing.