Sleep Lab, Department of
Psychology, University of Florence,
Yawning occurs more frequently in the early
morning and in the late evening, close to sleep
onset and after the awakening, and it might be
linked to sleep propensity. We aimed to study
yawning and its temporal distribution in morning
and evening subjects who display different
sleep-wake and sleepiness rhythms.
Sixteen healthy young adults (8
evening-types and 8 morning-types, matched for
age and gender) have been selected and
instructed to keep their habitual sleep
schedules and to signal every yawning occurrence
for three consecutive days.
Results show that evening-types yawn more
frequently than morning-types, particularly
during morning hours. Yawning frequency
decreases across daytime in evening-types
reaching its lowest level in the early evening
and increases thereafter. Instead, in
morning-types, yawning frequency remains quite
low during daytime and increases in the evening.
Moreover, both morning and evening types show a
progressive increase of yawning frequency in the
hours preceding sleep onset, whereas they differ
after the awakening.
Evening-types show a higher yawning
frequency that remains quite stable in the hours
following the awakening, while morning-types
display a decline in yawning frequency. Our
findings show that the temporal distribution of
yawning frequency differs between chronotypes,
supporting the hypothesis that differences in
sleep-wake rhythm affect yawning, which could
represent a behavioural sign of sleep
-Abe K et al.
Occurrences of Yawn and Swallow are Temporally
Related. Dysphagia 2014