Waking in the night, not trouble dropping off, was linked with daytime sleepiness
Researchers looked at how three common insomnia symptoms related to feeling sleepy in the day. People who woke repeatedly in the night tended to be sleepier, while people who struggled to fall asleep tended to be less sleepy.
At a glance
- People who woke repeatedly in the night were about 30% more likely to be sleepy in the day on two different tests.
- People who had more trouble falling asleep were about a third less likely to be sleepy on both tests.
- Waking too early in the morning wasn't linked with the overall pattern of daytime sleepiness.
- Study type
- Observational analysis of an existing long-running study
- Who took part
- 881 adults from the Wisconsin Sleep Cohort in the US
- Published
- Sleep Medicine, 2026
- Strength of evidence
- Early evidence An observational study of one group of people, with insomnia symptoms taken from questionnaires. The authors describe the links as modest.
What the researchers did
The researchers used data from 881 people in the Wisconsin Sleep Cohort, a long-running US study of adults' sleep.
They measured daytime sleepiness in two ways. One was a questionnaire about how likely you are to doze off in everyday situations. The other was a nap test in a sleep lab that measures how quickly you fall asleep during the day.
They then compared these results with three insomnia symptoms people reported: trouble falling asleep, waking repeatedly in the night, and waking too early in the morning.
What they found
The more trouble people had falling asleep, the less sleepy they tended to be in the day. They scored slightly lower on the questionnaire and took slightly longer to doze off in the nap test.
Waking in the night went the other way. People who woke more often scored slightly higher for sleepiness and were about 30% more likely to be sleepy on both tests.
Among people who often woke in the night, those who felt sleepy but didn't drop off quickly in the nap test had more symptoms of depression and anxiety.
The caveats
- Insomnia symptoms came from questionnaires, so they depend on how people remembered and rated their sleep.
- The study shows links, not cause and effect. It can't show that one symptom causes a particular kind of sleepiness.
- The links were modest, so a person's symptoms alone won't predict how sleepy they feel.
- All the participants came from one long-running study in one US state, so the results may not apply everywhere.
What this could mean for you
Insomnia isn't one thing. Struggling to fall asleep and waking in the night seem to affect the day differently.
If you feel very sleepy during the day, tell your doctor how your nights actually go, whether that's trouble dropping off, waking in the night or waking too early. Mention low mood or anxiety too, as they may be part of the picture.
The study
Wang Y, Xiong J, Zhang Q et al. Distinct daytime sleepiness phenotypes across insomnia symptom dimensions in the Wisconsin sleep cohort. Sleep Medicine, 2026; 149:109322.