Your discs fill with fluid while sleeping. The increased fluid increases disc pressure when bending by 300% and ligament stress by 80%, increasing the chance of injury to the discs. 90% of this fluid will dissipate within about 1 hour after after standing up.
To get out of bed:
1) Lie on back.
2) Draw legs to chest.
3) Brace abs and roll onto your side.
4) Push yourself into an upright position with your hands
...as you....
5) Swing your legs off the bad.

Probably have disc damage.
You may want to lie on your stomach for a few minutes before getting up. Also try the Cobra stretch after being up for 2-3 hours.
You may want to try a "SPINEWORX" - do a google search.

What you need is an evaluation by a spine specialist, either an orthopedic surgeon that specializes in spines or a neurosurgeon that specializes in spines only.

It sounds like you may be suffering from spinal stenosis, a narrowing of the canal that the nerves pass through in the vertebrae.

There can be several different causes of spinal stenosis and an MRI can help to determine what the cause is.

Typically the symptoms of spinal stenosis are extreme in the morning, as you describe, in getting out of bed, and do ease as the day progresses.

Do you find that you are bending forward without realizing it when you are standing and walking?

See a spine specialist for an evaluation and let the spine specialist order the MRI of your spine.
There are several different ways of having an MRI done and the spine specialist will know which you should have done.

Good luck

Fran