The sun 日 rises between plants 艹. The very similar radical 莫 stands for sunset. This seems bizarre, can be argued based on the characters for morning 朝 in comparison to evening 暮.
This radical can be seen as a person 人 who has the right leg horizontal 一. He is thus lying. (Further radicals with "person" are: sitting 匕, sitting cross-legged 夂, kneeling ⺈, skilled 才, bending マ,卩, slumped 㔾 or husband 夫)
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