SDI
Sleep Difficulties Inventory
This exploratory questionnaire describes sleep difficulties (falling asleep, night and early-morning awakenings, daytime impact) and what maintains them: arousal at bedtime, worries and beliefs about sleep, and habits and schedule. It covers the targets of cognitive behavioral therapy for insomnia and helps choose where to start. Two questions flag signs that call for a referral to a physician: snoring or gasping for air, and unpleasant sensations in the legs at rest.
- Number of questions
- 26 questions
- Estimated duration
- 6 minutes
- Language
- English
- Original name
- Sleep Difficulties Inventory
- Target audience
- Adults
- Category
- Sleep disorders
- Exploratory questionnaire
- Exploratory questionnaire
Preview of the 26 questions
Scoring & interpretation
Scoring
Insomnia
| Night and early-morning awakenings | 13 / 16 |
Waking during the night or too early in the morning, followed by difficulty getting back to sleep.
Areas to explore: the number and length of awakenings, what causes them (pain, needing to urinate, noise, thoughts), the time of final awakening; early-morning awakening with low mood points toward depression.
See also: ISI, PSQI.
| Falling asleep | 8 / 16 |
Difficulty falling asleep at the start of the night, despite fatigue.
Areas to explore: bedtime and how long it takes to fall asleep, what the person does when sleep is slow to come (staying in bed, getting up, looking at a screen), what helps or gets in the way.
See also: ISI, PSQI.
| Worries and beliefs about sleep | 7 / 16 |
Worry about not sleeping, monitoring of the night, and the feared consequences of poor sleep.
Areas to explore: the feared consequences of a bad night (health, work, mood), the amount of sleep the person considers necessary, what they do to protect themselves from a bad night.
See also: DBAS-16.
| Arousal at bedtime | 6 / 16 |
Thoughts and physical tension that keep the person awake when it is time to sleep, effort to fall asleep.
Areas to explore: the content of thoughts in bed (worries, the next day's schedule, sleep itself), signs of tension, the transition between evening activities and going to bed.
See also: Rumination and Worry Inventory.
| Habits and schedule | 6 / 16 |
Habits that maintain insomnia, often adopted to make up for lost sleep: time spent in bed, naps, screens in bed.
Areas to explore: bedtimes and wake times on weekdays and weekends, time spent in bed, naps, coffee, alcohol, and sleeping pills, screens in the evening.
| Daytime impact | 5 / 16 |
Effects of poor sleep on energy, concentration, and mood during the day.
Areas to explore: what the person attributes to sleep, activities cut back or canceled, daytime sleepiness (falling asleep unintentionally, while driving), which requires a medical opinion.
See also: ESS (sleepiness), MFI-20 (fatigue).
Medical screening
| Sensations in the legs | 3 / 4 |
An urge to move the legs in the evening at rest, which may suggest restless legs syndrome.
Areas to explore: when the sensations appear, whether movement relieves them, their effect on falling asleep; refer to a physician.
| Snoring and breathing problems | 0 / 4 |
Signs that may suggest sleep apnea.
Areas to explore: snoring and pauses in breathing noticed by others, daytime sleepiness, morning headaches; refer to a physician.
No validated clinical or psychometric cutoffs have been established for this test yet. The results should therefore be considered exploratory indicators, meant to support the clinical interview, not diagnostic findings.
Scoring
Each statement is scored from 0 (never) to 4 (very often) based on its frequency over the past month. Each of the six domains in the "Insomnia" block combines 4 statements spread throughout the questionnaire, giving a score from 0 to 16. The two signs in the "Medical screening" block (snoring or gasping for air, sensations in the legs) are each assessed by a single statement, scored from 0 to 4, at the end of the questionnaire.
Reading the profile
There is no total score. Within each block, domains are ranked from most to least elevated, each with a description of what it covers and points to explore in the interview. Falling asleep, night and early-morning awakenings, and daytime impact describe the complaint; arousal at bedtime, worries and beliefs about sleep, and habits and schedule describe what maintains it, the targets of cognitive behavioral therapy for insomnia. A frequent sign in the medical screening block calls for a medical opinion, particularly before any restriction of time in bed.
Clinical cautions
The questionnaire does not look for daytime sleepiness: falling asleep unintentionally, especially while driving, is not typical of insomnia and requires a medical opinion. Insomnia often accompanies depression, an anxiety disorder, or pain, and can be maintained by coffee, alcohol, sleeping pills, or other medications, which should be explored in the interview.
Limitations
This exploratory questionnaire has not undergone psychometric validation and has no cutoffs. It supports the clinical interview and does not provide a diagnosis.
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