The Indonesian government set 1 Ramadan 1446 AH on Saturday, 1 March 2025, after the new moon was sighted in Aceh Province, the same date adopted by several Islamic mass organisations (Janati, 2025). On construction projects, Ramadan is not a pause. Concrete pours, rebar work, scaffolding and earthworks continue, often carried out in the open by workers who fast from the predawn meal until sunset.
This literature review asks one question: what is known about the effect of Ramadan fasting on sleep, hydration and alertness, and what does it mean for organising work on construction sites? We read two reviews on sleep and cognitive function, one review on fluid restriction, one field study of heat exposure among construction workers, and the work climate provisions in Indonesia's regulation on the occupational safety and health of the work environment.
What Is Known
Leiper et al. (2003) reviewed studies of Ramadan fasting and found that most recorded significant metabolic changes but few resulting health problems. Common findings were irritability, headaches, sleep deprivation and lassitude. People who fast are clearly dehydrating during daylight hours, but it is not clear whether they remain hypohydrated through the month, and no detrimental health effect had been directly attributed to the negative water balance seen during Ramadan.
On sleep, the meta-analysis by Faris et al. (2020) pooled 24 studies with 646 participants from 12 countries. Average total sleep time fell from 7.2 hours a night before Ramadan to 6.4 hours during Ramadan, while daytime sleepiness on the Epworth Sleepiness Scale rose from 6.1 to 7.0. The researchers concluded that Ramadan brings roughly a 1 hour reduction in sleep and close to a 1 point rise in sleepiness score.
For construction work, heat matters as well. Measurements at 10 residential construction sites in Al-Ahsa Province, Saudi Arabia, from June to September 2016 showed workers exposed to excessive heat stress indoors and outdoors for much of the working day. A midday outdoor work ban from 12.00 to 15.00 did not reduce the risk effectively, because the highest exposure occurred between 09.00 and 12.00, with hourly mean wet bulb globe temperature (WBGT) values of 31 to 33°C (Al-Bouwarthan et al., 2019).
Where Findings Differ
The evidence is not uniform. Qasrawi et al. (2017) examined studies that controlled sleep schedule, sleep duration, light exposure and energy expenditure and found that these data do not support the idea that Ramadan fasting increases daytime sleepiness or alters cognitive function. The main change in sleep architecture was a smaller proportion of REM sleep. In everyday, uncontrolled settings, however, studies recorded sudden and significant delays in bedtime and wake time.
This difference needs to be read carefully. Fasting itself does not appear to be the main driver of reduced alertness. What changes is the daily pattern: a predawn meal, evening activities and broken sleep. A construction site is plainly an uncontrolled setting.
Gaps in the Evidence
We found no study that directly measured accident or injury rates among construction workers during Ramadan, in Indonesia or elsewhere. Participants in the Faris et al. (2020) meta-analysis were mostly young, with a median age of 23.7 years and 73 percent men, and were not doing heavy physical work in heat. The study by Al-Bouwarthan et al. (2019) took place in a desert summer and did not look specifically at workers who were fasting. Indonesia's humid tropical climate is different, so its WBGT values cannot simply be transferred.
In our view, the evidence supports one simple conclusion. On site, the risk during Ramadan is more likely to come from the combination of about 1 hour less sleep, fluids not replaced through the day and heat load than from fasting as a single factor. That combination is what needs managing, especially for tasks that demand close attention, such as work at height, operating heavy equipment and concrete pouring.
Sensible Arrangements
Minister of Manpower Regulation No. 5 of 2018 on Occupational Safety and Health of the Work Environment assesses hot work climates with the WBGT index. Where measurements exceed the threshold limit value, controls include removing or isolating heat sources, providing ventilation, providing drinking water, regulating or limiting exposure time, and using suitable work clothing and personal protective equipment (Kementerian Ketenagakerjaan [Kemnaker], 2018). These provisions continue to apply during Ramadan. Steps a project can take include:
- Measure WBGT at open work points from the morning onward, since field data show exposure can peak before midday (Al-Bouwarthan et al., 2019).
- Schedule heavy and high-risk tasks early in the shift, and give more frequent rest breaks in the shade towards midday.
- Provide drinking water and rest areas for workers who are not fasting, and make sure fasting workers can eat and drink properly at sunset before any evening overtime.
- Limit overtime after evening prayers and consecutive night shifts, because sleep is already about 1 hour shorter each night (Faris et al., 2020).
- Cover fatigue, headache and dizziness in the morning safety talk, and ask supervisors to stop work when a worker shows these signs (Leiper et al., 2003).
Available Support
Nusa Safety can help contractors and project owners measure hot work climates and workload through its Ergonomics and Work Environment Assessment, then translate the results into work schedules and job safety analyses in a Risk Assessment and JSA Workshop. For written Ramadan work arrangements that supervisors can actually use, the Nusa Safety team also prepares technical guidelines and SOPs. Nusa Safety issues internal training certificates only and is not a PJK3.
This article is general information and not legal or professional advice for any specific case.
References
- Al-Bouwarthan, M., Quinn, M. M., Kriebel, D., & Wegman, D. H. (2019). Assessment of heat stress exposure among construction workers in the hot desert climate of Saudi Arabia. Annals of Work Exposures and Health, 63(5), 505-520. https://doi.org/10.1093/annweh/wxz033
- Faris, M. A.-I. E., Jahrami, H. A., Alhayki, F. A., Alkhawaja, N. A., Ali, A. M., Aljeeb, S. H., Abdulghani, I. H., & BaHammam, A. S. (2020). Effect of diurnal fasting on sleep during Ramadan: A systematic review and meta-analysis. Sleep and Breathing, 24(2), 771-782. https://doi.org/10.1007/s11325-019-01986-1
- Janati, F. (2025, March 1). 1 Ramadhan 2025 serentak, Wamenag harap berlanjut pada penetapan Idul Fitri [1 Ramadan 2025 observed together; deputy minister hopes the same for Eid al-Fitr]. Kompas.com. https://nasional.kompas.com/read/2025/03/01/05372621/1-ramadhan-2025-serentak-wamenag-harap-berlanjut-pada-penetapan-idul-fitri
- Kementerian Ketenagakerjaan Republik Indonesia. (2018). Peraturan Menteri Ketenagakerjaan Nomor 5 Tahun 2018 tentang Keselamatan dan Kesehatan Kerja Lingkungan Kerja [Minister of Manpower Regulation No. 5 of 2018 on occupational safety and health of the work environment]. https://pasal.id/peraturan/permen/permenaker-no-5-tahun-2018
- Leiper, J. B., Molla, A. M., & Molla, A. M. (2003). Effects on health of fluid restriction during fasting in Ramadan. European Journal of Clinical Nutrition, 57(Suppl. 2), S30-S38. https://doi.org/10.1038/sj.ejcn.1601899
- Qasrawi, S. O., Pandi-Perumal, S. R., & BaHammam, A. S. (2017). The effect of intermittent fasting during Ramadan on sleep, sleepiness, cognitive function, and circadian rhythm. Sleep and Breathing, 21(3), 577-586. https://doi.org/10.1007/s11325-017-1473-x
