For insomnia on its own, usually not. Chronic insomnia is a clinical diagnosis — made from your history, your pattern over months, and a sleep diary. There is no test that shows it, and clinical guidance does not recommend a sleep study routinely for insomnia alone.
Which is the opposite of what most people expect, and it is worth understanding why before you spend money or a night in a lab.
What a sleep study measures
A polysomnogram records breathing, blood oxygen, heart rhythm, leg movement, eye movement and brain activity while you sleep. It is very good at finding things that happen to you during sleep.
Insomnia is not one of those. It is difficulty falling or staying asleep, with daytime consequences, over months — and the defining features are the pattern and the distress, neither of which a single night in an unfamiliar room captures well. People with insomnia often sleep unusually well in a lab, or unusually badly, and neither result changes the diagnosis.
The measure that actually characterises insomnia severity is a questionnaire, not an instrument.
When a study is genuinely worth asking about
The purpose is to find a different disorder hiding underneath, or alongside, the insomnia. Raise it with a clinician if any of these apply:
- Loud snoring, particularly if someone has noticed you stop breathing, or you wake gasping or choking.
- Daytime sleepiness — genuinely falling asleep when you did not intend to, at a red light, in a meeting, in front of the television mid-afternoon. This is different from being exhausted, and the distinction matters.
- Restless legs in the evening, eased by moving them, or a partner reporting repeated kicking through the night.
- Morning headaches, waking with a dry mouth, or needing the bathroom several times a night.
- Acting out dreams — shouting, punching, falling out of bed.
- High blood pressure that is difficult to control, atrial fibrillation, or a neck circumference at the larger end. These raise the prior probability of apnea.
- A behavioral program that has been run properly and has not moved anything. A stalled course of CBT-I in someone who genuinely held the schedule is a reasonable prompt to look further.
Insomnia and apnea together
The two coexist often enough that the combination has its own name in the sleep literature. It matters practically: treating the insomnia while leaving apnea untreated tends to disappoint, and treating apnea does not automatically resolve an insomnia pattern that has been running for years.
It also matters for safety. Deliberately restricting time in bed when you have significant untreated daytime sleepiness is not appropriate, which is why the screening questions come before any window is calculated and why every article here repeats the same list.
