There is a widespread notion that plants steal oxygen from the air at night and should not be used in bedrooms. Plants use carbon dioxide during the day to produce photosynthesis and oxygen that is emitted into the air. At night when there is no light for photosynthesis, the process is reversed and plants use a slight amount of oxygen. However, the oxygen debt at night is far less than the oxygen added during the day. So feel free to keep plants in your bedroom as long as there is enough light to keep them growing. The plants will not only add oxygen, but they help filter air pollutants.