The pineal gland produces melatonin, a hormone that regulates sleep. Reduced levels of light—most critically, reduced levels of blue light—signal...
GMAT Two Part Analysis : (TPA) Questions
The pineal gland produces melatonin, a hormone that regulates sleep. Reduced levels of light—most critically, reduced levels of blue light—signal the pineal gland to begin producing melatonin. In the past, the production of melatonin would start at dusk, peak in the middle of the night, and then taper off near dawn. Today, the nighttime use of cell phones, tablets, and computers whose screens emit blue light, has changed the timing of melatonin production, and sleep patterns have been adversely affected. Furthermore, smaller screens viewed at closer range intensify the adverse effects. In a recent study of the nighttime use of screen-based devices by 10,000 teenagers, researchers concluded that the longer the teens viewed their screens before going to bed, the longer they took to fall asleep after going to bed. Thus, the study showed that as the 1 increased, the 2 increased.
Select for 1 and for 2 the phrases that create the statement that most logically completes the passage. Make only two selections, one in each column.
Phase 1: Owning the Dataset
Argument Analysis Table
| Passage Statement | Analysis & Implications |
| "The pineal gland produces melatonin, a hormone that regulates sleep" |
|
| "Reduced levels of light—most critically, reduced levels of blue light—signal the pineal gland to begin producing melatonin" |
|
| "Today, the nighttime use of cell phones, tablets, and computers whose screens emit blue light, has changed the timing of melatonin production" |
|
| "In a recent study... the longer the teens viewed their screens before going to bed, the longer they took to fall asleep" |
|
Key Patterns Identified
- Established Facts: Blue light suppresses melatonin; screens emit blue light; reduced melatonin delays sleep
- Trend: Positive correlation between screen viewing duration and sleep onset delay
- Valid Inference: Increased screen time → increased blue light exposure → increased melatonin suppression → increased time to fall asleep
Phase 2: Question Analysis & Prethinking
Understanding Each Part
- Part 1 Focus: What variable increased in the study (the independent variable)
- Part 2 Focus: What consequence increased as a result (the dependent variable)
- Relationship: These form a cause-and-effect relationship observed in the study
Valid Inferences
- For Part 1: The study measured "length of time teens spent viewing screens before bed" - this is what varied
- For Part 2: This increased screen time led to "delay in melatonin production" which caused "longer time to fall asleep"
Phase 3: Answer Choice Evaluation
Analyzing Each Option:
"size of the screens the teens viewed"
- What it claims: Screen size was the measured variable
- Fact Support: Passage mentions smaller screens have worse effects, but the study didn't measure size variation
- Logical Validity: Not what the study measured
- Part Suitability: Neither part
"length of time the teens spent viewing their screens before going to bed"
- What it claims: Duration of screen exposure was measured
- Fact Support: Directly stated: "the longer the teens viewed their screens before going to bed"
- Logical Validity: This is exactly what the study varied
- Part Suitability: Perfect for Part 1
"use of apps to control the amount of blue light"
- What it claims: Blue light filtering was involved
- Fact Support: No mention of blue light control apps in the passage
- Logical Validity: Pure speculation
- Part Suitability: Neither part
"delay in melatonin production after the teens went to bed"
- What it claims: Melatonin production was delayed
- Fact Support: Blue light delays melatonin + longer screen time = more delay
- Logical Validity: Necessary biological consequence of increased blue light exposure
- Part Suitability: Perfect for Part 2
"distance from which the teens viewed their screens"
- What it claims: Viewing distance was measured
- Fact Support: Passage mentions distance affects intensity, but study didn't measure this
- Logical Validity: Not what the study examined
- Part Suitability: Neither part
Final Selection
- Part 1: "length of time the teens spent viewing their screens before going to bed" - This is explicitly what increased in the study
- Part 2: "delay in melatonin production after the teens went to bed" - This is the biological mechanism that explains why sleep onset was delayed
Verification
The completed statement reads: "Thus, the study showed that as the length of time the teens spent viewing their screens before going to bed increased, the delay in melatonin production after the teens went to bed increased."
This perfectly captures the study's finding and explains the biological mechanism behind it!