Nasal cycle

The nasal cycle is a physiological condition that occurs naturally in the human nose. It involves the alternating partial congestion and decongestion of the nasal cavities. This cycle is controlled by the autonomic nervous system and is a normal physiological response, not an indication of nasal congestion or health issues.

The nasal cycle was first described by the German physician Richard Kayser in 1895. It is characterized by a periodic change in airflow resistance between the two nostrils, with one nostril experiencing increased airflow while the other experiences decreased airflow. The cycle typically shifts from one nostril to the other every 2 to 6 hours.

This phenomenon is believed to serve several functions, including enhanced olfaction (the sense of smell), regulation of air humidity and temperature before the air reaches the lungs, and prevention of drying in the nasal passages. The nasal cycle is also thought to facilitate sleep by promoting breathing through one nostril, which can help regulate body temperature and blood pressure.

The regulation of the nasal cycle is complex and involves various factors, including the sympathetic nervous system and parasympathetic nervous system, hormones, and physical activity. External factors such as allergies, infections, and environmental conditions can also influence the cycle.

Understanding the nasal cycle is important in the field of otolaryngology (ear, nose, and throat medicine) and can have implications for the treatment of nasal conditions, such as chronic sinusitis and deviated septum. It also has relevance in sleep medicine, particularly in the context of conditions like sleep apnea, where nasal obstruction can play a significant role.