Laziness and sleepiness are not the same thing, you can attribute tiredness to sleepiness but laziness can be somebody that is not tired but don't want to work. It's natural to become tired after a stressful work, at that point the body needs rest and sleep can be a remedy. A lazy person wants to rest and sleep all day when they have things to do and their body can carry them.
I understand your point as you are trying to proof that if you give yourself a real time to rest and you fall asleep so fast your feeling sleepy not lazy as someone who have been in stress for long require it.
By definition they are not the same thing. But one can led to the other. This means if you do sleep on a regular basis when it is not a symptom of any diagnosis people will consider you lazy. For instance, you kept on sleeping in your office or business place every day, what do you think your colleague or business partners will say if not about you been lazy.