Development of a scale to assess the diurnal impact of insomnia

Area of Science:

• Psychiatry
• Psychometrics
• Sleep Medicine

Background:

• Insomnia significantly impacts daytime functioning, yet specific assessment tools for this diurnal dysfunction are limited.
• Understanding the daytime consequences of insomnia is crucial for effective clinical management and patient care.

Purpose of the Study:

• To develop and validate the Insomnia Diurnal Impact Scale (IDIS) for assessing the daytime effects of insomnia.
• To evaluate the psychometric properties and diagnostic accuracy of the IDIS in diverse populations.

Main Methods:

• The IDIS, a six-item scale, was developed and its psychometric properties analyzed in student, psychiatric patient, and community samples.
• Reliability (internal consistency, test-retest) and validity (correlations with other scales, sensitivity, specificity) were assessed.
• The scale's ability to differentiate between insomniacs and non-insomniacs based on ICD-10 criteria was examined.

Main Results:

• The IDIS demonstrated strong internal consistency (Cronbach's α = 0.86, English version = 0.93) and good test-retest reliability (0.79).
• A single factor explained nearly 60% of the variance, indicating a coherent construct.
• The scale showed moderate to high correlations with other measures and adequate sensitivity and specificity in differentiating insomnia.

Conclusions:

• The Insomnia Diurnal Impact Scale (IDIS) is a reliable and valid instrument for assessing insomnia-related diurnal dysfunction.
• The IDIS is suitable for use in primary care and mental health settings for both general and psychiatric populations.
• The scale effectively discriminates between individuals experiencing insomnia and those who are not.