A healthy night's sleep
Approximately 1/3 of our life is spent sleeping, so avoiding breathing and absorbing toxins while sleeping could greatly reduce our overall exposure.
Cotton grown for textile use can be heavily sprayed up to 30 to 40 times a season with pesticides so poisonous they gradually render fields barren. Most cotton sheets are treated with a formaldehyde -based finish that reduces wrinkling and give it that "nice feel" that used to be accomplished by ironing.
The average mattress seems to contain around a pound of fire retardants called PDBE which was only banned in the US in January 2005, so the mattress you currently sleep on probably contains it. See more info on fire retardants. The "memory foam" polyurethane mattresses (eg. Temper-Pedic) are loaded with chemicals and especially toxic.
For the most healthy night's sleep use a natural latex (rubber) or cotton organic (chemical free) mattress, and organic mattress toppers, sheets, pillows and blankets. Cotton flannel and cotton jersey sheets do not contain formaldehyde, but unless they're labeled organic, they most likely have been grown with pesticides. Avoid polyester/cotton blends and fabric labeled permanent-press, easy-care, or no-iron. These all have formaldehyde.