The Pittsburgh Sleep Quality Index (PSQI) is a self-report questionnaire used to measure sleep quality. It offers a standardized method for evaluating an individual’s sleep habits and disturbances over a one-month period. This tool is frequently applied in both clinical and research environments to gain insight into sleep patterns.
The Seven Components of Sleep Quality
The PSQI is structured around 19 questions that provide information for seven distinct components of sleep. These components collectively create a detailed picture of an individual’s sleep experience. Each component targets a specific aspect of sleep, allowing for a comprehensive evaluation beyond simply how many hours were slept.
- Subjective sleep quality, which is a person’s overall rating of their sleep.
- Sleep latency, referring to the amount of time it takes to fall asleep after getting into bed.
- Sleep duration, accounting for the total number of hours a person actually sleeps each night.
- Habitual sleep efficiency, which calculates the percentage of time spent in bed that is dedicated to sleeping.
- Sleep disturbances, which includes reasons for waking, such as using the bathroom, experiencing pain, or having bad dreams.
- The use of sleeping medication, whether prescribed or over-the-counter.
- Daytime dysfunction, which examines the impact of poor sleep on daily life, such as feeling tired or having trouble staying enthusiastic.
Calculating the Global PSQI Score
The process of calculating the global PSQI score involves converting responses from the 19 questions into a final number. Each of the seven components is assigned a score ranging from 0 to 3, where a 0 indicates no difficulty and a 3 signifies severe difficulty.
For example, the score for sleep latency is determined by how long a person reports it takes them to fall asleep. A time of less than 15 minutes scores a 0, while 16-30 minutes equals a 1, 31-60 minutes results in a 2, and more than 60 minutes gets a score of 3. Similarly, sleep duration is scored based on the number of hours slept, with more than seven hours scoring a 0 and less than five hours scoring a 3.
Once a score from 0 to 3 has been assigned to each component, these scores are added together to produce the global PSQI score. This final score can range from 0 to 21, with higher scores indicating a greater degree of difficulty with sleep.
Interpreting the Global Score
The global PSQI score provides a straightforward way to understand a person’s overall sleep quality, and a widely accepted cutoff point is used to interpret the results. A global score of 5 or less is generally considered indicative of good sleep quality, while a score greater than 5 suggests poor sleep quality.
A higher global score points to more severe or frequent problems across the various aspects of sleep. For instance, a person with a high score might have trouble falling asleep, wake up often during the night, and experience significant tiredness during the day.
It is important to recognize that the PSQI is a screening instrument, not a standalone diagnostic tool. While a high score can identify individuals who may have sleep problems, it does not provide a specific diagnosis. Individuals who receive a score greater than 5 are often advised to consult with a healthcare professional for a more thorough evaluation and to recommend appropriate interventions.