Objectives:
The aim of this study was to assess the prevalence and severity of subjective daytime functioning impairment among people with insomnia complaints. Another goal was to establish its relationships with age, gender, type and duration of subjective insomnia.

Methods:
Study group consisted of NATPOL study participants – 2,413 people (1,245 women and 1,168 men) aged 18–79. We extracted group with declared insomnia complaints, consisting of 1,221 people (736 women and 485 men) aged 18–79. Data on insomnia symptoms characteristics, their duration and subjective functioning impairment were further analyzed.

Results:
Functioning impairment was declared by 825 people (67.7% of those who declared subjective insomnia) and it was more common in women. It was most common among people with insomnia complaints lasting over two weeks – 72.4%. In people with symptoms lasting less than two weeks or for a few days it was 70.7% and 64.9% respectively. People with insomnia symptoms lasting over two weeks accounted for 20% of group with severe functioning impairment. For shorter duration of symptoms it was 8.6% and 6.9% respectively. Among people with mild functioning impairment, persons with symptoms lasting for a few days and less than two weeks were predominant – 32.5% and 35.3% respectively. In people aged 18–24 years mild functioning impairment was predominant (66.66%).

Conclusions:
Subjective daytime functioning impairment is common in people declaring insomnia symptoms. It is more common in women and its prevalence and intensity are greater in people with longer duration of sleep problems. Its prevalence is not correlated with age and it is the mildest in people aged 18–24.