- Diagnostic criteria of sleep problem questionnaire.
| Types of sleep disturbance | Items |
|---|---|
| Difficulties initiating sleep | Question 1 |
| Difficulties maintaining sleep | Question 2 |
| Early awakening | Question 3 |
| Subjective impairment | Question 4 |
| Insomnia | Question 1/2/3 + Question 4 + Question 5 + Question 6 |
| Irregular sleep - wake type | Question 7/8 + Question 4 + Question 5 + Question 6 |