Changes in airway resistance during sleep onset

Area of Science:

• Sleep Science
• Respiratory Physiology

Background:

• Ventilation naturally decreases during sleep compared to wakefulness.
• Increased airway resistance is hypothesized as a key factor in this ventilatory change.
• Ventilatory changes during sleep onset correlate with transitions in electroencephalogram (EEG) activity, specifically between alpha and theta states.

Purpose of the Study:

• To investigate if the increase in airway resistance during sleep onset also occurs at alpha-theta EEG transitions.
• To determine the relationship between airway resistance and ventilation changes during sleep onset.

Main Methods:

• Three young healthy males underwent approximately 15 sleep onsets each.
• Measurements included ventilation and airway resistance using an esophageal balloon.
• Experiments were conducted with and without nasal occlusion to assess its impact.

Main Results:

• Changes in airway resistance, when affected by state, occurred at alpha-theta EEG transitions, mirroring ventilation changes.
• The magnitude of ventilatory changes and their association with airway resistance varied significantly between subjects.
• Nasal occlusion did not appear to be a primary factor in the observed state-related changes.

Conclusions:

• Inspiratory airway resistance is a significant factor in state-related ventilation changes at sleep onset.
• The individual contribution of airway resistance to these ventilatory changes can differ substantially among people.