I don't really have an answer to this. Feeling tired has always been a big problem for me regardless of how many hours I spent sleeping. I presume it perhaps has had something to do with depression & anxiety. Or maybe it has something to do with the way my body functions in general... my metabolism or some such thing.

I recall reading an article on the subject of sleep in our local newspaper a while back. Basically what it said was that it's not simply the number of hours a person sleeps that's important but also the quality of sleep a person gets. So a person could well be getting sufficient numbers of hours of sleep. But if it's a disturbed, restless sleep, the person will still wake up tired. Unfortunately I don't recall that the article offered any suggestions for how to improve one's quality of sleep. That was left for reader's to figure out for themselves.

Here are links to some articles, from PsychCentral's archives, on the subject of sleep. The first article, by DocJohn, provides links to a number of additional articles as well:

Sleep Disorders & Insomnia Guide

The First Line of Treatment for Insomnia That'll Surprise You

9 Tips for A Good Night's Sleep

There's More to Sleep than Bedtime

How to Get a Good Night's Sleep — Even When You're Depressed

https://blogs.psychcentral.com/nutri...-nights-sleep/