Traditionally, some textbooks from the United States used a system of six kingdoms (Animalia, Plantae, Fungi, Protista, Archaea/Archaeabacteria, and Bacteria/Eubacteria) while textbooks in Great Britain, India, Australia, Latin America and other countries used five kingdoms (Animalia, Plantae, Fungi, Protista and Monera).
For other uses, see Placebo (disambiguation) and Placebo effect (disambiguation). The placebo effect can be produced by inert tablets, by sham surgery, and by false information, such as when electrical stimulation is turned off in those with Parkinson's disease implanted brain electrodes.
The lack of sunlight causes our levels of serotonin, a brain chemical (neurotransmitter) that impacts our mood; and melatonin, a hormone that impacts our mood and sleep patterns; to drop. This causes depression, a drop in energy, and general irritability.