Yes, a pillow should be used to support the Head for Sleeping and Its GOOD for your back and your neck. That is the short answer.
Anatomically speaking, it's ideal for the head and the neck to be using a supportive pillow while sleeping at night. Naturally your cervical spine is not straight when looking at it from the side - instead it has a natural c curve in it and you need to get a cervical support pillow that allows for that c curve. This is called the cervical lordosis. So in my opinion, a contoured neck pillow will help the most with this.
From the Front (Anterior View): Your spine should be straight up and down
From the Side (left lateral View): There is C Curve in the neck "Cervical Curvature"
From the Back (Posterior View): Your spine should be straight up and down
Think of your spine like a kinetic chain too. What is happening at the top of the spine will affect what is happening in the other parts. If you are aligned in the neck area, that will continue onto the mid back and into the lower back.
Check out Arc4life's Linear Gravity Neck Pillow - it will allow you to have the proper c curve while you are sleeping. This particular neck pillow has TWO neck rolls on it for sleeping on your back and side. One neck roll is smaller and firmer, and the other neck pillow is broader and softer. You pick the side that is most comfortable for you to sleep on.
The nice thing about the arc4life linear gravity neck pillow is that it comes in three sizes: Small, Medium and Large. If you are under 5 ft with a petite frame choose the small, Between 5 ft- 5'10/5'11 choose the medium. Anybody over the 6 ft should choose the large pillow. But these are not hard and fast rules either. If for example you are 5 ft, but always use a standard size pillow, choose the medium. Contact Arc4life to help you get the right pillow.
Choosing a neck pillow that is contoured versus a neck pillow that is flat is more ideal and healthier for your neck. You need support for your head and neck when you sleep because naturally we have curves in our spines. Overall healthier for your whole spinal system which ultimately houses the nervous system.