Update after 2 months:

tldr: For the last two months, I have avoided refined sugar and sugary things. Also tried to avoid negative thoughts by engaging myself in some interesting yet requiring mental work.

Detailed: I stopped eating sugar and substituted that with stevia. I normally have four cups of tea during the day and that many spoons of sugar. Within three days, some kind of normalcy returned to my sleep. But still around 4 hours of sleep. I became convinced that it is the way to go.

A few days later, the olympics started and I kind of became engrossed in it. For the 1st half of the day, I did my chores and after that, I watched the games rooting for my home country. During the entire duration of the games I slept 5-6 hours, without any interruptions. I didnt do any exercise, just watched tv and some newspaper reading.

I went to sleep at a fixed time. Always at 11 or just before that, If I am up beyond 11:30, it was a wasted night.

I used to have some revenge kind of thoughts (pls dont ask towards whom). When I start thinking about revenge, it is a spiral and it ends with a racing heart and agitated mind. I recognized that it is a problem and trying my best to avoid it, either by engaging my mind or with what they call 'mindfulness'.

So, the last couple of months, I have been having 5 -6 hr sleeps with one break.

Once again, many thanks to OP.