Droopy Seedlings

currently doing a window sill grow with only natural light, before i transplant them outside.
all four plants are autoflowers.
seedlings are about a week old now and have started drooping and falling over. is this due to too much/ too little water or what?

Pics... Need pics usually. How long is the stem? Could be to far from the light and the stalk is to skinny and long.... Need pics again

Pictures not possible due to lack of camera! Sorry. I'd say the stem is about 3cm, thinking of adding more soil so only the top part of the stem and small leaves are exposed.

My guess would be lack of light - which happened to me when I had propagator on the window sill. Yeah adding more soil should be fine, or stringing it to a support if you can do this without damaging it.