I read cats should sleep between 15-20 hours a day.
But TC never sleeps nowhere near that much. In fact, I would go as far as saying he sleeps between 6-10 hours a day and never more.
I often feel he sleeps so less because he is never fully comfortable with me in the home, so that's why he is nearly always awake when I am up and about. Sometimes in the evening, he sits on my landlady's bed on his hind legs for hours - he looks so alert and scared
What I would like to know is can such less sleep have a harmful effect on him for the future? May it take years off his life? Is there anything I can do to make him sleep more?
I'd stop stressing about this Ahmed. If he needs sleep, he'll find somewhere peaceful where he feels he won't be disturbed and just get on with it! You may be right that if he's feeling anxious he will be more alert, but some cats are just more active than others. My latest two cats slept at least 20 hours a day (although they are quite a lot older), but some of my previous cats were happy and healthy on very much less than that. It just varies with each cat. You don't need to MAKE him sleep more, but giving him a bit of peace and quiet will give him the opportunity to sleep whenever he chooses.
I worry because I was reading about cats who can die suddenly from heart failure, and if he isn't sleeping as much as he should and is stressed out a lot, it might take him to his grave early, and that would make me very sad, especially as he has spent his whole life in a small flat, and although my landlady takes good care of him, I can't but help feel sad that he hasn't lived life to the full.
Cats who die suddenly from heart failure tend to have underlying heart disease...
I think you're perhaps obsessing a little about your landlady's cat. I know you love him but really, he sounds fine to me! Your job as a tenant is to respect him and enjoy him.. it's up to your landlady to worry about his wellbeing
Unfortunately I do have a nature where I can worry a lot about things.
At the end of the day, I will probably be moving abroad for work in a few months, and I will probably never see him again. That makes me really sad, but that's just the way it goes. I just want to make sure he has a good life ahead of him and the stress of having me around doesn't end up harming him in the future.