This is a very common condition caused by a disturbance in the tear film. Tears are made up of water, oils, vitamins and mucous.
If the balance is disturbed the tears are unable to coat the eye sufficiently. This causes the eye to dry out and become gritty, in turn the eyes become heavy and may ache. Also the eye may water, especially in the wind.
Artificial tears are very useful for restoring tear function. There are a variety of tear substitutes on the market for mild, moderate and severe dry eyes. It is often trial and error in finding ones that suit, all must be used at least four times a day for relief to be acheived.
It is also worth remembering that most preparations are cheaper over the counter than on prescription!
Dry eye drops I personally recommend are Systane, Clinitas and Hylotears (Hyloforte).