They can be bugs or dust mites or molds(fungi or mildew). These are microscopic organisms, which are related to spiders, live in many homes. Too small to see with the naked eye, dust mites thrive in warm, humid environments — eating dead skin cells and nesting in dust-collecting bedding, fabric, carpet and furnishings.
To remove them from your home,first of all open all the windows and doors and let ample sunshine come in. , remove drapes, feather pillows, upholstered furniture, non-washable comforters and soft toys. Replace carpets with linoleum or wood. Vacuum soft furniture and curtains as well as floor Wash carpets and upholstery with special cleaners, such as benzyl benzoate or tannic acid spray. Wash all bedding in hot water (hotter than 130°F) every 7 to 10 days. Don't use mattress pads. Cover mattress and pillows with plastic covers. Lower the humidity in your home.Can be done by using dehumidifiers.You can also install special air filtering devices in your bedroom.
Hope it helps.Take care and regards.