Enhancing Slow Wave Sleep in Depression

Duration of Stage N3 Sleep

Change in number of minutes of stage N3 sleep across the night

Percentage of N3 Sleep

Change in percentage of stage N3 sleep across the night relative to total sleep time

Word Pairs Memory Task

Participants are presented with 44 word-pairs to learn during an encoding phase and immediately tested by presenting one word and being asked to recall the paired word. Participants are tested again in the morning in the same way - one word of the pair is presented and they are asked to recall the other. To avoid recency and priming effects, the first 4 and last 4 word pairs presented are not scored. Participants are scored on accuracy (0-36 words). A smaller decline in accuracy from the immediate recall (evening) to delayed recall phase (morning) indicates better verbal memory performance.

Choice Reaction Time (CRT)

CRT measures the time it takes for a person to respond to a stimulus when there are multiple possible responses to choose from. It is a measure of how quickly someone can process information, make a decision, and initiate a motor response. Participants are presented with 20 trials of stimuli to respond to. The test is scored on average reaction time where a longer reaction time indicates worse processing speed performance.

Digit Symbol Substitution Test (DSST)

133-item neuropsychological assessment that measures cognitive functions like processing speed, attention, and visuoperceptual skills. It involves matching symbols to numbers based on a provided key and is often used to assess cognitive impairment. The number of correct symbols within 120 seconds constitutes the score (0-133 max score) where a lower score represents greater impairment in processing speed and attention.

One-Back Working Memory Test

Cognitive test that assesses an individual's ability to hold and manipulate information in their short-term memory. The one-back working memory test is scored by assessing both accuracy and average response time. Accuracy is measured as the percentage of correct responses (hits) to target stimuli, while response time reflects the average speed at which participants identify matches. Higher accuracy and faster response times generally indicate better working memory performance. Participants are presented with 20 total trials (potential accuracy score, 0-20; potential reaction time 0-3 seconds). Both the accuracy and reaction time scores are z-scored and then combined to create a single composite score for the test.

Epworth Sleepiness Scale

The Epworth Sleepiness Scale (ESS) is an 8-item self-administered questionnaire to assess an individual's level of daytime sleepiness. Scores range from 0 to 24, with higher scores indicating greater daytime sleepiness. A score of 10 or higher generally suggests excessive daytime sleepiness, possibly indicating a sleep disorder.

Pittsburgh Sleep Quality Index

The Pittsburgh Sleep Quality Index (PSQI) is a 19-item self-report questionnaire used to assess sleep quality and disturbances over a one-month period. Scores range from 0-21, where a higher score indicates more severe sleep disturbance. Generally, a global score of greater than 5 indicates poor sleep quality.

Morningness-Eveningness Questionnaire

The Morningness-Eveningness Questionnaire (MEQ) is a 19-item subjective assessment designed to assess individual differences in morningness and eveningness - the degree to which respondents are active and alert at certain times of day. The MEQ is scored by summing the responses to 19 questions, with each question offering multiple choice answers that are assigned numerical values. Scores range from 16 to 86, with lower scores indicating an "evening" chronotype and higher scores indicating a "morning" chronotype.