Damp around master bedroom window

I have double glazing white aluminium windows throughout my house.

All windows appear fine except the master bedroom where after the winter, the inside frames of the windows are covered with black damp mildew, the wall around the windows are covered in damp and there is a pool of water on the windowsill.

Can anyone advise what needs to be done?

Do you have adequate ventilation in the room. Like a wall vent that is not blocked up.

Just out of interest, it this the only room in the house regularly used for sleeping in?

A dehumidifier might help? We got one in homebase last year and it's brilliant - helps the clothes dry so much faster on the clothes horse too by taking the extra moisture out of the air.

We had mould under our bedroom window too, used Dettol Mould & Mildew remover then bought the dehumidifier and set it going - it's certainly helped it not come back as badly. Also a friend of mine said to leave the bedroom window open for about 10 mins each day which I think has also helped.

M

There is a wall vent over the door - it doesn't appear to be blocked up on either side

I'll try the dehumidifier but I was hoping to establish the cause - there doesn't appear to be anything different between this room and the other rooms expect thats where we sleep - the other rooms are unoccupied except for when guests stay.

Your breathing at night produces a lot of moisture. Its enough to make the windows moldy. There is probably not any difference with this window and the others. Do you have an ensuite? Do you thrown damp towels on the rads in the main bedroom.
All these will add to the mositure.
Good ventilation is the key. A dehumidifier is useful (it needs to be a proper electric one, not a gel refillable one), it helps to remove the water without having to improve the ventilation, but it needs to be left on a lot and they do use electricity.
Try opening the windows a bit and see how that works. Leaving the ensuite fan on for longer is also very improtant.

Try searching the forums for damp/mildew etc, theres loads of other posts.