If I feel like I have a cold, or run down in any way, I have absolutely zero shame about going to bed as 5 or 6 PM.
The best way for your body to fight those things is for you to stop moving, and lie down.
Sleep is when your natural defenses spring into action; not while you’re working an 8, 10, or 12 hour day.
(Neither while you’re watching TV late at night.)
Your body knows exactly what to do and how to do it.
You don’t have to give it instructions.
You just have to get out of its way.