Student nurse here. It’s all related to the effects the med has on your body. So if it causes drowsiness, needs to be taken on an empty stomach, if it can cause dizziness, nausea, orthostatic hypotension, and many other side effects. When you are asleep you don’t notice the effects as bad. Sometimes it’s preference as well. I don’t like how one of my meds makes me feel so I take it right before bed so the adverse effects don’t bother me.
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