Your husband probably had a syncope
. The syncope is caused by reduced blood supply to the brain for a variety of reasons. Once a patient becomes flat (like after falling) the blood supply is restored and consciousness is regained. Syncope is a fairly common experience and may be seen a few times in a large number pf patients. When it becomes very frequent then it needs to be evaluated. Another possibility that it could have been a type of convulsion
needs to be considered and evaluated by the treating doctor.