We made be made from the material of stars but we are not stars. So any comparison to stars in this respect is crazy. (It's like saying we eat oranges so why don't we look like an orange?)
Sleep is not a part of human nature. It is a physical requirement for human bodies.
There is no “think” about it. Sleep is vital to physical and mental health.
You may not be “awake” during sleep but your brain is very busy.
REM (dream) sleep is where your brain consolidates everything you have experienced, learned, etc each day. It is when short term memory is processed and converted to long term memory. If this doesn't happen you will lose your short term memories. You will not be able to even think normally if you are deprived of REM sleep for too long. During REM sleep your RAS is activated. This means that your muscles can't work so that no matter what you dream it stays in your head rather than being translated into action. There are exceptions to this like sleep waking and REM sleep disorder but they are all disorders of sleep not sleep as it should happen.
In deep sleep (stage 4) your body heals itself. If you don't get deep sleep your health will suffer as a result.
Studies have been done where college students are kept from sleeping for a number of days. The results show mental illness and possible health troubles. When the students are allowed to sleep again these problems go away.
So get your sleep every night (8–9 hrs uninterrupted sleep) and your mind and body will thank you by working as well as they are able to work.