Which Sleep Habit Matters Most? 203 Students Offer a Clue

Not the one most people blame first. A new open-access study of 203 university students in Malaysia, Singapore's neighbour, found that a busy mind at bedtime and a poor sleep setting were linked to worse sleep quality, while having a regular routine added little once those two were counted. It is a small, one-time survey, so it shows a pattern and proves no cause. Still, it is a useful nudge for anyone in a warm, humid place who has tidied their bedtime schedule and still sleeps badly.

What did the Malaysian study actually measure?

Researchers at Tunku Abdul Rahman University of Management and Technology and Zhejiang University surveyed 203 students in the Klang Valley, the Kuala Lumpur area. The students were recruited online through social media, were about 21 years old on average, and were mostly female (54.7%) and Chinese (95.5%). People with chronic illness, a past or current sleep disorder, or antipsychotic medication were excluded.

Each student filled in two standard questionnaires. The Sleep Hygiene Index (SHI) scores 13 everyday habits, and the Pittsburgh Sleep Quality Index (PSQI) scores how well someone has slept over the past month. On the PSQI, a score above 5 marks a "poor sleeper". The group averaged 6.50, so as a whole they sat on the poor side of that line.

What did they find?

Overall, worse sleep hygiene went with worse sleep quality (r = 0.365). The more interesting part came from splitting the habits into three groups and testing them together.

| Habit group | Link to poor sleep quality | Statistically significant? | | --- | --- | --- | | Pre-sleep cognitive-emotional arousal (worry, mental activity, emotional distress at bedtime) | β = 0.256 | Yes (p < 0.001) | | Sleep environment (physical sleep conditions) | β = 0.206 | Yes (p = 0.003) | | Sleep routine and behavioural activation (irregular schedules, stimulating things before bed) | β = 0.083 | No (p = 0.254) |

Together the three groups explained 15.1% of the differences in sleep quality, so most of the picture sits outside what this survey measured. The authors suggest that bedtime arousal and the sleep setting are closer to the problem, so routine habits matter less once those are accounted for.

Does other research back up the "busy mind" finding?

Some, yes, using different methods.

• Sleep lab data. A 2020 study in Sleep Medicine followed 52 adults (18 with insomnia disorder, 34 healthy sleepers) through two nights of polysomnography. Higher pre-sleep cognitive arousal went with a longer time to fall asleep, lower sleep efficiency and shorter total sleep time, in a group that mixed healthy sleepers and people with insomnia.
• Students in Croatia. A two-wave study of 302 undergraduates at the University of Zagreb found a two-way link between stress and sleep quality. Stress predicted sleep problems more strongly (β = 0.345) than sleep problems predicted stress (β = 0.203), and rumination partly explained the link.

Three different designs point the same way. That makes the Malaysian result more believable, though none of them proves that quieting your mind will fix your sleep.

What are the study's limits?

• It is a snapshot. A one-time survey cannot show whether a busy mind causes poor sleep or poor sleep feeds a busy mind. The Zagreb study suggests both happen.
• Some measures were weak. The cognitive arousal group had only three questions and modest reliability (Cronbach's alpha 0.515). The environment group had just two.
• The sample is narrow. Nearly all participants were young Chinese students recruited by convenience sampling, so the results may not match your life.
• Self-reported only. Nobody wore a sleep tracker or sat in a lab.

What can you try tonight?

The study did not test any fixes, so treat these as sensible experiments rather than proven cures. The authors themselves point to relaxation techniques, mindfulness and structured wind-down routines for the mind, and to improving the sleep setting.

• Park the to-do list early. Jot tomorrow's tasks down an hour before bed so your head does not have to hold them.
• Give your mind a runway. Swap work messages and doomscrolling for something low-key, such as a shower, light stretching or a familiar podcast.
• Fix the loudest environment problem first. In a humid bedroom that is often heat and stickiness. Cooler air, breathable bedding and a fan are the obvious levers. A cooling weighted blanket is one option for people who like the feel of pressure without the heat, though this study did not test bedding. The specifications page lays out what that design does and does not claim.
• Do not abandon your schedule. Routine was not significant here, but that does not make a steady bedtime harmful. It may simply matter less than the other two once they are handled.

If poor sleep lasts for weeks or is hurting your days, speak with a clinician.

Sources

1. Chen AYQ, Low CS, Kan KC, Ng KS. "Association between multidimensional sleep hygiene and sleep quality among university students." Discover Public Health, published 5 October 2026: https://link.springer.com/article/10.1186/s12982-026-02749-6
2. Kalmbach DA, Buysse DJ, Cheng P, Roth T, Yang A, Drake CL. "Nocturnal cognitive arousal is associated with objective sleep disturbance and indicators of physiologic hyperarousal in good sleepers and individuals with insomnia disorder." Sleep Medicine 71:151-160, 2020. DOI: https://doi.org/10.1016/j.sleep.2019.11.1184 (PubMed: https://pubmed.ncbi.nlm.nih.gov/32247571/)
3. Petak A, Maricic J. "The Role of Rumination and Worry in the Bidirectional Relationship Between Stress and Sleep Quality in Students." International Journal of Environmental Research and Public Health 22(7):1001, 2025. DOI: https://doi.org/10.3390/ijerph22071001