You can. If you have a venous ulcer, then wearing a low compression stocking at night is often recommended. Otherwise, there is probably no need. It is important to remember that the compression you should use at night (15-20 mm hg) isn't adequate for when you you are up and walking around. Then you probably need 30-40 mm hg.
Depends. If you are having a bad bout of leg swelling, then wearing stockings at night can help bring the swelling down quicker. Once one gets to the maintenance phase of wearing compression socks to keep swelling from occurring or worsening, then there is no need to wear compression socks at night.
Stockings. There is no benefit to use stockings when you sleep at night as your legs are elevated and the venous system is on the same level as the heart.
Depends. In certain medical conditions it is advised to wear compression stockings as much as possible, even at night. This includes cases of venous statis ulceration, severe lymphedema or severe edema of other causes, & when acute blood clots are in the legs. In other circumstances, such as in most cases of varicose veins or more mild leg swelling, there is not much of a benefit at night when your legs up.