TST is defined as which sleep metric?

• A. Shortness of Breath
• B. Selective Serotonin Reuptake Inhibitor
• C. Total Sleep Time
• D. Sleep Disordered Breathing

Answer: (C)

Total Sleep Time is the total amount of time a person spends asleep during a sleep period. It’s measured by summing all the sleep intervals from sleep onset to the final awakening and excludes periods of wakefulness. This metric shows how long you actually slept, not just how long you were in bed or trying to sleep. It’s often used with Time in Bed to compute Sleep Efficiency (TST divided by Time in Bed) and helps assess whether someone is getting sufficient sleep. For example, being in bed for eight hours but awake for about 40 minutes during the night yields a Total Sleep Time of roughly seven hours and twenty minutes. The other options describe a symptom, a medication type, or a condition, not a sleep duration metric.