A new study shows that chronic poor sleep increases immune cell numbers and promotes inflammation, but good, consistent sleep helps maintain a healthy balance of white blood cells and supports normal immune function.

The study involved 14 healthy adults who experienced two six-week sleep protocols – one in which they got sufficient sleep (about 7.5 hours) every night and one in which they got about 6 hours of sleep every night – separated by a six-week break. The investigators measured inflammatory markers in the participants' blood every morning and afternoon of the last two weeks of each protocol.

They found that when the participants didn’t get enough sleep, their afternoon blood samples had higher levels of immune cells called monocytes and markers of immune activation compared to when they got enough sleep. Poor sleep also induced epigenetic changes in stem cells that produce immune cells, reducing their progeny’s diversity and tipping the balance of immune cell production toward an inflammatory profile.

Sleep has profound effects on human health. Not getting enough sleep or having poor, fragmented sleep drives an increase in the production of myeloid cells, a type of white blood cell that predominates in aging and activates inflammasomes – drivers of inflammation.

These findings suggest that sleep preserves healthy immune cell production, thereby reducing inflammation. Learn more about the health benefits of sleep in this episode featuring Dr. Matthew Walker.

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