Sleep is brainwashed

Sci­en­tists from Boston Uni­ver­si­ty have demon­strat­ed how dur­ing sleep the brain is flushed with cere­brospinal flu­id, which removes tox­ic waste prod­ucts from its tis­sues.

The study involved 13 healthy adults aged 23 to 33 years. When they fell asleep and were in the stage of non-REM sleep, sci­en­tists mon­i­tored their brain activ­i­ty using mag­net­ic res­o­nance imag­ing (MRI). At the same time, they were inter­est­ed in the activ­i­ty of neu­rons and the move­ment of oxy­genat­ed blood. With the help of one of the vari­eties of MRI, researchers were also able to observe the move­ment of cere­brospinal flu­id.

It turned out that at the time of the appear­ance of delta waves, when blood is direct­ed from the brain, its tis­sues are washed by pul­sat­ing waves of cere­brospinal flu­id. Pre­vi­ous stud­ies sug­gest that with the flow of cere­brospinal flu­id dur­ing the peri­od of activ­i­ty of delta waves, tau pro­tein tan­gles are washed out, the accu­mu­la­tion of which in brain tis­sues leads to demen­tia (demen­tia).

Sci­en­tists clar­i­fy that dur­ing slow sleep, brain neu­rons do not need an active sup­ply of oxy­gen, and the blood sup­ply to the brain decreas­es. At the same time, the pres­sure in its tis­sues drops, and due to this, cere­brospinal flu­id active­ly enters there. Its waves bathe the brain every 20 sec­onds.

Pre­vi­ous­ly, cere­brospinal flu­id pul­sa­tion, blood flow, and brain waves were mea­sured sep­a­rate­ly, but now we can say that they are all com­bined in a sin­gle process designed to cleanse the brain of tox­ic waste prod­ucts.

Indeed, in old­er peo­ple with Alzheimer’s dis­ease, the pul­sa­tion of cere­brospinal flu­id dur­ing non-REM sleep is much weak­er than in peo­ple who do not suf­fer from cog­ni­tive impair­ment. That is, in Alzheimer’s dis­ease, there is an accu­mu­la­tion of tau pro­tein, which destroys the brain and leads to demen­tia.