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Nonrestorative Sleep Scale (NRSS)
Availability
Please visit this website for more information about the instrument: Nonrestorative Sleep Scale (NRSS)
Classification
Exploratory: Myalgic encephalomyelitis/Chronic fatigue syndrome (ME/CFS)
Short Description of Instrument
12-item scale for assessment of non-restorative sleep
 
Population: Adults (age range of subjects 18-85)
Comments
The scale demonstrated an internal reliability α = 0.88 and test-retest reliability r = 0.72.
Scoring
The scale consists of 12 items evaluating four factors: refreshment from sleep, physical/medical symptoms, daytime functioning, and affective symptoms. Of the scale’s twelve items, ten employ Likert scales with values ranging from one to ten, while an additional two items offer five options. Some items are worded positively (with ten indicating very good sleep quality), while others are worded negatively (where ten refers to very poor sleep quality). The scale’s scoring system was designed such that all items are given a weighted score from one to five. Though this complicates scoring, it ensures that all questions are weighted equally. Negatively worded items are reversed before scoring, meaning that higher scores on the scale indicate less NRS. Global scores can range from 12 to 60.
Rationale/Justification
Validity: 1) Tested against polysomnographic measurements -- however all subjects at sleep clinic, not just those with non-restorative sleep; 2) correlation with other scales: FSS, CES-D, PSQI, Toronto Hospital Alertness Test, Athens Insomnia Scale
 
Reliability: The scale demonstrated an internal reliability α = 0.88 and test-retest reliability r = 0.72.
 
Advantages:
1) Short, understandable items, 2) Helps assess the most common sleep disturbance symptom, non-restorative sleep. This scale is referred to in a paper by Russell et al.,2017 which noted that there are few treatment trials of ME/CFS assess sleep and that unrefreshing sleep was an important symptom to assess.
 
Limitations:
1) Items were developed from 2 focus groups and narrowed down using analytic methods. However, focus groups were narcolepsy and obesity, not subjects with non-restorative sleep, and 2) Not tested on ME/CFS subjects before.
References
Wilkinson K, Shapiro C. Development and Validation of the Nonrestorative Sleep Scale (NRSS). J Clin Sleep Med. 2013;9(9):929–937.
 
Russell C, Kyle SD, Wearden AJ. Do evidence based interventions for chronic fatigue syndrome improve sleep? A systematic review and narrative synthesis. Sleep Med Rev. 2017;33:101–110.
Recommended Instrument for
ME/CFS
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