If you are doing HIIT sessions shortly before going to bed, then you’re not going to be getting maximum benefit from them.
Intervals are going to jack up your metabolism after you do them, so going to sleep soon after is kind of counter productive, because your metabolic rate is going to slow down. End result: you will burn less calories and fat.
You’re not going to be getting the full benefits of intervals by doing them so close to bed time.
Try and do them earlier if you can. Ideally with at least a few hours of being awake between training and bedtime.
I guarantee that you’ll get better fat loss this way. Your metabolism will be roaring after a serious interval session, so take full advantage of it.
By going to sleep you’re basically telling your metabolic procresses to slow down, and that’s making things more difficult than they need to be.
I know that might not always be possible. It’s just something to think about…