Very complete exposé on sleep. I don't have anything to add here 

The gadgets as smart wearables, offsprings of the very technology that created artificial lighting part of the issue is a good way to assess how much and how well one sleeps.

Some apps will even denote the amount of REM, deep sleep, sleep heart rate dip, and HR variability ... It may seem extreme but can he helpful.

It is important to strike a balance and to also know that waiting the weekend to catch up on sleep is not clinically considered valid. Supposedly, one does not have the capacity to make up for lost sleep time!

All these sorts of biorythms were sorted out and understood by yogis and folks in ancient traditions. It is really modern lifestyle and schooling that fostered the habits of sleep deprivation.

One glaring example is that of medical students. According to the hyprocratic oath, they shan't do harm. But how is operating on a patient while sleep deprived healthy or advisable to any sain person?

From having had the opportunity to sleep in close environment with Rishi on one occasion or two, I was amazed at the man's ability to sleep as I'd say "like a baby".

In older age most people lose the ability to sleep enough. I suppose the hormonal secretions are already out of tune after years of abuse from relentless, abusive and exploitative work schedules, or excessive worries over personal and family dramas/concerns.

Though I never had the conversation with him regarding what I observed, I remain in admiration. He has explained in his writings proper routines to unplug and prepare the system for rest based on keen understanding of the life force's participation.

Only now that I have more control over my daily schedule can I appreciate and value the benefits of longer sleep, and it is such a blessing as well as a luxury that is out of reach for most, primarily out of not knowing and/or from life obligations.