the heart sends signals to the brain to sleep

After a heart attack, the heart sends signals to the brain to create a greater desire to sleep and thus speed up the healing process, since rest can help reduce inflammation.

PHOTO EPA/PA/Stefan Rousseau

Scientists from Mount Sinai Hospital in New Yorkone of the world’s leading centers for cardiac and vascular research and surgery, and the results of its work, which are published this Wednesday in the journal Naturedemonstrated for the first time how the heart and brain communicate with each other through the immune system to promote sleep and recovery after a major cardiovascular event such as a heart attack.

The results highlight the importance of increasing sleep after a heart attack and suggest that adequate sleep should be a focus of clinical treatment and care after a heart attack, even in intensive care units where sleep is often disrupted, along with cardiac rehabilitation.

The researchers first used mouse models to discover this phenomenon; They induced heart attacks in half the mice and performed high-resolution cellular and imaging analyses, and used implantable wireless electroencephalography devices to record electrical signals from their brains and analyze their sleep patterns.

After the heart attack, they observed a threefold increase in slow-wave sleep, the deep phase of sleep characterized by slow brain waves and less muscle activity. The increase in sleep occurred quickly after the heart attack and lasted a week.

When researchers studied the brains of mice that had had a stroke, they found that immune cells called monocytes were recruited from the blood into the brain and used a protein called tumor necrosis factor (TNF) to activate neurons in an area of ​​the brain called the thalamus. , which caused an increase in sleep.

This occurred several hours after the heart attack, and nothing similar happened in mice that did not have heart attacks, the researchers explained in a review submitted to the journal.

The researchers then used sophisticated techniques to manipulate TNF neural signals in the thalamus and found that the sleeping brain uses the nervous system to send signals to the heart to reduce cardiac stress, promote healing and reduce cardiac inflammation after a heart attack and therefore reduce cardiac inflammation. improve recovery.

Sleep disturbance

To better determine the role of increased sleep after a heart attack, the researchers also interrupted the sleep of some mice.

They found that mice with interrupted sleep after a heart attack had increased sympathetic responses to cardiac stress and inflammation, leading to slower recovery compared to mice with continuous sleep.

Research group Mount Sinai Hospital He also conducted several human studies; First, they studied the brains of patients one or two days after a heart attack and found an increase in the number of monocytes compared to people without heart attacks or other cardiovascular disease, mirroring the results of their studies in mice.

They also analyzed the sleep of more than 80 heart attack patients for four weeks after the cardiovascular event and followed them for two years.

The patients were divided into two groups—good sleepers and poor sleepers—based on the quality of their sleep in the four weeks after the heart attack, and the researchers found that patients who slept poorly in the weeks after the heart attack had a worse prognosis.

They had twice the risk of developing another cardiovascular disease than good sleepers, and good sleepers had significant improvements in heart function, while poor sleepers had little or little improvement .