Several recent studies have demonstrated the relationship of sleep to brain function. In particular, how we need sleep for normal brain function. In a recent study, a system called the glymphatic system, which serves to rid the brain of toxic substances, was found to be ten times more active during sleep than during wakefulness. In another study, myelin, a substance that insulates nerves and is destroyed by Multiple Sclerosis, was found to be produced at twice the rate during REM sleep.
Now comes a fascinating study revealing actual death of brain cells occurring with sleep deprivation. Published in the March issue of The Journal of Neuroscience, researchers from the Perelman School of Medicine have demonstrated that prolonged wakefulness in mice was linked to loss of neurons in a critical area of the brain called the locus coeruleus (LC). This is an area of the brain that is vital for alertness and cognition.
The mice were observed following periods of normal sleep, short wakefulness, or extended wakefulness attempting to duplicate a shift workers schedule. They found that after several days of extended wakefulness the mice exhibited a 25% loss of neurons in the LC. Apparently, a protein called SIRT3, which protects the cell from oxidative stress and death, was depleted. However, after short periods of sleep loss, the levels of SIRT3 increased and were protective.
The authors point out that for years we have assumed a full recovery of cognitive abilities after short and long-term sleep loss. However, some studies have failed to show retrieval of these functions even after three days of recovery sleep. Now we have a study that demonstrates substantial brain cell death with prolonged periods of insufficient sleep.
Although this study involves mice and not humans, the areas of the brain and their function are quite similar. In addition, SIRT3 has been well demonstrated to function in a similar manner in humans. In fact, the authors intend to study autopsy specimens of the LC in deceased shift workers, as well as find out if turning up the production of SIRT3 in vulnerable areas of the brain can prove to be effective in preventing cell death.
I find this to be a very important study. It is one of the first to demonstrate that prolonged inadequate sleep may result in irreversible brain death. It may help us to explain permanent cognitive dysfunction in those who chronically go without enough sleep. It also goes a long way to debunk the myth that you can catch up on your sleep on your days off or on the weekend. As of now, over 33% of the population admits to sleeping less than seven hours, and many of them less than five. This study should help to demonstrate what a high price these people might be paying.
