Why Should I Sleep After a Heart Attack?
Sleep is something that fascinates all of us. From checking our smartwatches to keeping a journal, we all are obsessed. So too are Scientist’s around the globe. Understanding why we sleep and how we can harness the power of sleep could be key to advancing medicine as we know it.
Research just published in the journal ‘Nature’ has explored just that. The research team wanted to understand what role sleep has, if any, following damage to the heart.
What do we already know?
Changes of sleep patterns in patients with heart disease has been observed for decades.
Sleep plays a critical role in a dialogue between the brain and the heart by regulating neural and immune circuits which impact on the heart’s function.
Disturbed sleep increases the risk of myocardial infarction (MI) (‘Heart attack’) as well as other heart conditions.
Signals from the hypothalamus in the brain, modulate immune cell production, impacting conditions like atherosclerosis. Conditions which lead to heart disease.
What did they find?
First the team looked at sleep in mice. In mice who had heart disease (Atherosclerosis) had altered sleep rhythms. Specifically they had an increase in the amount of time spent in slow wave sleep (SWS / Deep sleep). In mice who had cardiac injury caused by MI, they spent significantly longer asleep (up to 85%) in the first 7 days following the MI. And a greater proportion of the sleep was deep or SWS. This raises the question of why? Why is sleep changed after MI? What purpose does it serve?
Turning to the brain, the researchers noted in the first 24 hours after an MI, a large increase in the number of a particular immune cell called monocytes was present. These monocytes moved from the circulating blood system into the brain. Through a series of experiments including sham controls, and cell signal blocking, the research team demonstrated these immune cells that were causing the change in sleep patterns, specifically the increase in the amount of SWS/ deep sleep.
So now from these experiments the researchers have demonstrated:
Sleep, specifically slow wave sleep, increases after an MI
This is controlled by cells of the immune system
What is the purpose? What does it mean for me?
In a group of human volunteers who were recovering from acute coronary syndrome (heart attacks / angina), those who slept poorly were found to have significantly worse recovery than those people who slept well.
In fact, neuroinflammation post-MI was shown to have a protective role, enhancing sleep to suppress excessive sympathetic activity, reduce inflammation, and facilitate cardiac recovery.
Why is this important?
This study provides evidence that in the days after a cardiac event such as a heart attack, promoting sleep is important to protect the heart from further damage and promote recovery. The heart protects itself by activating the immune cell network, signalling the brain to change the pattern of sleep and thus serving to try and protect itself from further damage.
This evidence will inform changes to treatment and rehabilitation plans for patients and hopefully will improve the quality of life for you, the people.
Original Research Article:
Huynh, Pacific, et al. "Myocardial infarction augments sleep to limit cardiac inflammation and damage." Nature 635.8037 (2024): 168-177.
