The onset of rem sleep the release of neurotransmitters called

stops; monoamines.

Explanation:

Monoamines are biochemical substances derived from amino acids through the decarboxylation process. The main monoamines are catecholamines (namely dopamine, norepinephrine, epinephrine), originating from tyrosine; tryptamine-derived serotonin and histamine from histidine. All monoamines are directly related to emotional disturbances and can be blocked through REM sleep. This is because the onset of REM sleep prevents the release of these neurotransmitters called monoamines.

biology is the study of life. it is the study of living organism.

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.