Essence of the Upanishad is - ‘I am the universe, and the universe is in me’. This means every experience has to be experienced within this body. We leave this body only once and not every night.
There is a far deeper mystical phenomenon which occurs during sleep. Sleep is like the story of ‘Cinderella’. The party is over every evening. We must go home (aa ab Laut Chale). Home? Where is Home? Home is where nature is. To reach nature, we first need to drop our mind and then witness all the emotions held throughout the day to release our trapped breath. Breath begins to travel back to its home in collective unconscious. We do that through RAM and NON-REM stage of sleep. We first enter in NON REM stage where breath begins to liberate from the layers of subconscious and in the REM stage, wisdom from the past is given to us in the form of dreams and insights. This wisdom is hidden or coded in each cell. We go deep into each cell where the subconscious links to the collective subconscious where it has home. This is nature.
In other words, sleep is an automated, well-regulated meditation process to connect to the intelligence coded in our body. In sleep, we only go deep into the body which is the home to our subconscious and carries the code of purpose of our life.
#2 I do not have issues with sleep
According to google, sleeping aids is 67.8 billion USD market. You are a part of that market. Do not trust yourself that you sleep well. Sleep is prevention and sleep is the cure. You are aging faster due to your sleep quality despite expensive anti-aging measures, yoga, gym, diet and Botox. Bill Gates has taught us that when a system gets overloaded, it crashes. This is what you do. You crash when the burden of your emotions and thoughts cannot be handled any more by your body. This is because your mind has been consuming the oxygen meant for the body. In such a situation, nature helps you by suspending emotions and thoughts to rejunate the body. But you wake up with the same thoughts and emotions held by you the previous day. You are aging faster because your mind does not reset. This is where you lose control of your mind and now your mind controls you. This is already the seeding of sleep disorder.
The definition of sleep disorder is not confined to only being sleepless. It is true it rejuvenates. But to say that we must sleep to rejuvenate is to say water is wet. Rejuvenation is its nature and not the purpose. Over centuries, the whole science behind sleep which our ancestors followed by pursuing a lifestyle is distorted. It is now reduced to seeing sleeping as a compulsion or a necessary evil.
#3 I must sleep for 8 hours
This is the funniest thing you make yourself believe in. Yes, this is a great guideline to know but the number of hours of sleep depends on how loaded you are with your emotions and how active your mind is. An infant sleeps most of the hours because he does not have a thought or emotion of this birth, but subconscious memories of the previous births are being released and wisdom and purpose is being brought in awareness.
An aged person does not need so much sleep because they have resolved thoughts and emotions of the past. A yogi stays in Yog Nidra throughout the day and night. Lovers remain in a half sleep state most nights and yet they do not feel sleep deprived through the day. A mother sleeps very little and yet she is round the clock energetic.
It is a function of your lifestyle which tells you how loaded your mind is and how many emotions are stuck in your subconsciousness. The fewer they are, the less hours you would need for sleep.