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Findings from NFS studies






Click on the timeline above to learn more about our findings from each of our previous NFS studies.

Our sleep intervention studies

    There are many forces at work that govern adolescents' sleep schedules.

  Apart from characterizing the negative effects of sleep restriction on neurocognitive and metabolic functions, our lab has also sought to actively promote sleep extension in adolescents through the implementation of interventions such as (1) delaying school start time and (2) sleep education.


















Delaying school start times

    In 2016, we collaborated with Nanyang Girls High School to delay school start time from 07:30 to 08:15. After 1 month, students demonstrated improvements in sleep duration, daytime alertness and well-being, and these positive changes were maintained 9 months after. Our findings clearly show that starting school later is feasible and can lead to sustainable benefits.


Students, parents, and teachers are joint stake-holders in any initiative to start school later, as school start times inevitably affect all three groups. Encouragingly, the majority of students, teachers, and parents were supportive of the schedule change during the intervention period. This positive response is vital for the success and continuity of the initiative especially in a culture that has internalised notions prioritising academic success over the importance of sleep.



Sustained benefits of delaying school start time on adolescent sleep and well-being




Starting school later is key to solving sleep problem faced by Singapore students

Letting students sleep in is a move worth emulating

Teachable moments from one school’s move to let students sleep in

Your opinion: Should Singapore schools start 45 minutes later?


News articles:

A big difference in students, after Nanyang Girls starts school later at 8.15am

Teens do better when they start school later in the day according to science​

New study adds evidence for benefits of starting school later in the morning



Sleep education


    In 2018, we partnered with Raffles Institution (Secondary) to trial a sleep education program. The intervention group received a sleep education program (SEP) and the active control group received a healthy living program (HLP). Both groups underwent a 4-weekly class-based education program. The SEP students learned about the importance of sleep, the barriers to getting enough sleep, and how to improve their time management to increase their sleep opportunity. The HLP group learned about various health-related topics, but not about sleep.


    Improvements in sleep knowledge at the 1-month follow-up were found in the SEP group relative to the HLP group. However, although students were receptive of the program and reported their intentions to create more time for sleep, no changes in sleep behavior were found for the sleep education group.


     This intervention highlighted to us that having in-depth knowledge about the importance of sleep may not be sufficient to change sleep behavior. The sobering truth is that a combination of methods, including sleep education, later school start times and parental involvement will be needed to encourage and enable long-lasting changes in sleep duration in adolescents.

ST Podcast: Why sleep habits need to be formed when young

Commentary: Always tired yet can’t fall asleep? It’s a wake-up call to sleep better


Look out for our upcoming published work!

Ecological model of teen sleep.png

How we measure sleep

There are many ways scientists assess sleep. In our lab, we use subjective measures such as questionnaires and sleep diaries, as well as objective measures such as actigraphy and polysomnography.




An actiwatch is a wrist-worn monitoring device frequently used in research settings to objectively evaluate sleep by recording and allowing comparisons of levels of light intensity and physical activity across a 24-h period.



Polysomnography (PSG) is deemed the ‘gold-standard’ to measure sleep objectively. This is a technique whereby electrodes are placed on the scalp and face to monitor brain activity, eye movements, and muscle tone during sleep. Sometimes, a nasal airflow sensor and pulse oximeter may be included to monitor airflow and the level of oxygen in the blood. For our NFS studies, we use a portable PSG device by Somnomedics so that participants can move around freely even with it attached to the head. The use of this device on a scale such as ours is unprecedented.


We thank the National Medical Research Council, National Research Foundation and Far East Organization for their funding and support of our work.

We thank Nanyang Girls Boarding School for providing excellent infrastructural support without which the Need For Sleep studies would not be possible.


We are grateful to all the school principals and teachers who have helped us with advertising and recruitment for our studies.


Interested in supporting our work? Find out how

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