A good serum is something I never go without morning or night. I wish I had started that habit in my 20's. I have tried most of them and here are a few of my favorites that actually made a difference in my skin.
Map
Small amount goes a long way. Leave on while you sleep and safe enough to apply around your eyes.
Retinol Fusion PM Night Serum - Peter Thomas Roth
On the expensive side but noticed a difference within a few days of using.