Muscle and bone structure
Growing older naturally changes the structures of your chest and spine, such as the thinning of bones. This could change the shape of your ribcage as it shrinks in size and leaves less room for expansion. The muscles that support breathing become weaker and overall it becomes harder to breathe.
Lung tissue
The tissues of your lungs keep your airways open. As you get older, these tissues weaken and lose elasticity. As a result, you lose the ability to control your airways. In addition, the shape of your air sacs malform and are unable to perform its process of oxygen-carbon dioxide exchange as effectively. Both factors result in increased difficulty and more effort in breathing.
Nervous and immune systems
When your body is not performing at its full capacity, the risk of infection increases. As you age, the nerves in your airways that trigger coughing are less sensitive and it becomes harder to clear out toxins by coughing. Also as you age, your immune system is weaker and recovery times become prolonged to fight against infection.
Overall, the common problems you may find with age include:
Increased lung infections
Shortness of breath
Low oxygen levels
Abnormal breath patterns, which can result in sleeping problems