Hyaluronic Acid Serums are everywhere at the moment. Its really important to keep the skin hydrated and at this time of the year when the air is a little drier (well everywhere other than Glasgow) sometimes our skin needs a little something extra to help with this.

I'm a bit obsessive about putting on moisturiser. I don't suffer from dry skin other than a few patches around my nose, but I do have very dehydrated skin. Its important to know the difference between these two skin types to make sure you are chosing the correct products.
Dry skin types tend to have some rough or flaky patches whereas dehydrated skin often looks normal but feels tight and can look dull.
One of my favorite moisturisers for dehydrated skin is the Kiehls Ultra Facial Cream. Its great for both day and night. Recently though due to the summer (sort of summer) and the rubbish aircon in my office I've needed a bit more help with hydration.
I've been using a Hyaluronic Acid Serum from Juliette Armand (£26.00) in the evening before I apply my night cream.

Hyaluronic Acid might sound a little scary but its actually a gel-like, water holding molecule which is naturally found in our bodies. Studies have found it to increase hydration and encourage the production of collagen in the skin. It helps to retain 1000 times its weight in water which is why it makes such an effective product for hydration.
I like to apply this right after I've washed my face at night, to try and lock in as much moisture as possible. Once it has sunk in I'll apply my normal night cream.
I've used several different hyaluronic acid products in the past and I'm a big fan. If you suffer from dehydrated skin definitely give it a go.