Question on the eighth precept of Vipassana

That's pretty the best way to follow the conducts of the Arahats, yet a mat to get not dirty and catch no cold, a simple, wouldn't be wrong.

Depends on where you live. If one lives in a cold place sleeping directly on the floor might not be a good idea for health-related reasons. Instead using a low bed or very thick mattress would be good. Otherwise one can use a simple bed.

The most important thing though is to be mindful of the arising of any liking and attachment towards the bed especially when waking up in the morning and experiencing the warmth and cosiness of the bed.

When we think about the precepts, it's always best to remember that the Buddha advocated the middle path: the path that avoids extremes. It's common even today for wealthy people to have thick, luxurious mattresses that go well beyond the needs for comfort towards pure sybaritic pleasure. See for instance:

We don't have to sleep on a mattress on the floor; a simple frame with a simple bed for the simple purpose of sleep is perfectly appropriate. Asceticism can be as much a trap for the ego as conspicuous wealth if one engages in self-denial for the purpose of demonstrating ones own superiority.

There's at least one Q&A on that topic at suttacentral:

• Eighth Precept: What Constitutes “High and Luxurious”?

In summary the interpretation of that precept seems to vary:

I’ve seen different Theravada communities set various expectations as to how their 8 Preceptors should follow Precept No 8.

I gather that "a bed" is permitted, only not a "high and luxurious" one.

So something like "a mat" may be OK; or perhaps a thin camping-mattress.

Good sleeping is good for the meditation, but sleeping too much is bad for the meditation.

Normal people can't have good sleeping on the cold concrete cement, but better on the hard wooden bed and too much better on the king's bed.

In the same case on the difference situation, some day normal people is sick hardly, maybe the king's bed is better, then his healthy is return and the king's bed is too much good again.

On every case the wholesome meditation's development is the measure.

The way to know whether "what's good" and "what's bad" is the Mastery Jhana Meditation like the Buddha is teaching "Keeping on the concentration meditation because the jhana-mastery can see the truth".

Normally monks used to have a bed height below the knee and simple one with two inches mattress. Here we need to understand the concept behind the precept. According to buddha one should refrain from the mind, having luxury, not in physically. But avoiding physical luxury automatically refrain from the luxury mind. Because of that we used to live with simplicity. Lord buddha preferred to live with nature like under the tree, near the waterfall, with very minimal facilities. But Buddha accepted palaces and comfortable things chairs beds etc.

The reason behind is until we become enlightened we have to follow the said path. If we use more comfortable things automatically mind sets to those comfort and used to seeks those comfort. It may hinder the following the middle path for the enlightenment. That is why Buddha asked us to avoid two extremes an be in the middle path always. Hope you got the idea.

Another important thing you should not touch the buddhism in words and its meanings. Words there to explain the consequences or the occurrences. We need to feel it from the mind, catch them using meditative wisdom. For that, first you need to learn the concept using words. Example:- Matters 4 main Elements. Earth, Water, Fire and Air. In Earth element, it is spreading through hard to softness you have to feel each points differences with the next point. Actually this can not e done using words even you understood using meditative wisdom. If so lord Buddha would have already told us. But once you start experiencing the differ of the matters little by little you will understand the wisdom of lord buddha.

This is how monks used to have their beds. This will clear your answer for your question by seeing these pictures. 01. 02. 03. 04.

May Triple Gem Bless you!!!