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Blackwell Science, LtdOxford, UKSBRSleep and Biological Rhythms 2004; 2: 000–0001446-92352004 Japanese Society of Sleep Research22135143Original ArticleRamadan Fasting and SleepA BaHammam

Sleep and Biological Rhythms 2004; 2: 135–143

ORIGINAL ARTICLE

Effect of fasting during Ramadan on sleep architecture, daytime sleepiness and sleep pattern Ahmed BAHAMMAM Sleep Disorders Center, Respiratory Unit, Department of Medicine, College of Medicine, King Saud University, Riyadh, Saudi Arabia

Abstract Fasting during Ramadan is distinct from regular voluntary or experimental fasting. This project was conducted to objectively assess the effect of Ramadan fasting on sleep architecture, daytime sleepiness and the circadian cycle of melatonin level. Eight healthy volunteers reported to the Sleep Disorders Center on four occasions for polysomnography and multiple sleep latency tests: 1) an initial visit for adaptation; 2) 2 weeks before Ramadan (BL); and 3,4) during the first and third weeks of Ramadan (R1, R3). Salivary melatonin level was measured using radioimmunoassay. Sleep latency at night was significantly shorter and the amount of rapid eye movement sleep was significantly less, at R3 compared to BL. There was no difference in multiple sleep latency test data between BL and Ramadan. Although melatonin level kept the same circadian pattern at BL, R1 and R3, it had a flatter slope and a significantly lower peak at midnight (00:00) at R1 and R3. This study showed a significant reduction in sleep latency and rapid eye movement sleep during the third week of Ramadan fasting. Otherwise, there was no significant effect of Ramadan on sleep architecture and assessment revealed no increase in daytime sleepiness. Although melatonin level had the same circadian pattern during Ramadan, the level of the hormone dropped significantly from baseline.

Keywords: Ramadan, fasting, sleep, melatonin.

INTRODUCTION Fasting during the month of Ramadan is prescribed for Muslims as one of the five major pillars of Islam. For Ramadan, Muslims abstain from food, drink and smoking during the daytime; i.e. from dawn to sunset. The pattern of meals changes as well, with two to three main meals usually taken: breakfast at sunset, dinner after night prayer (Esha), and another meal before sunrise (Suhur). Over one billion Muslims fast during this month every year. During Ramadan, physiological changes are expected Correspondence: Dr Ahmed BaHammam, FRCP, FCCP, Sleep Disorders Centre, Respiratory Unit, Department of Medicine 38, College of Medicine, King Saud University, Box 2925, Riyadh, Saudi Arabia. Email: [email protected] Accepted for publication 20 April 2004

© 2004 Japanese Society of Sleep Research

to result from both long-term dietary restriction and partial sleep loss. Islamic fasting is distinct from regular voluntary or experimental fasting by the limited duration of the fasting period within the 24-h cycle; by abstinence of the performer of the fast from drinking and smoking; by the change in the usual circadian pattern of eating which causes caloric intake increases at night; and by the month-long duration of the practice which may allow adaptation to the new regimen. Therefore, one may assume that physiological changes occurring during Islamic fasting may be different from those during an experimental fast.1 Moreover, Ramadan is a lunar month, meaning that its position within the calendar year changes over time. The Islamic (Hijra) year, containing 354 days, is 11 days shorter than the Gregorian year. In a previous work using the Epworth Sleepiness Scale (ESS) with a group of medical students, we found a significant increase in daytime sleepiness during

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Ramadan even though the participants’ total sleep time during Ramadan did not differ from baseline.2 The fact that meals for Ramadan are taken exclusively at night has been proposed as a mechanism possibly affecting circadian rhythm during the fast.3 Recently, Rocky et al. reported increased objective daytime sleepiness during Ramadan fasting using the Multiple Sleep Latency Test (MSLT) associated with decreased total sleep time (TST), increased sleep latency and changes in diurnal body temperature.4 However, in the protocol of the above paper, dinner (the main meal) was given shortly (1 h) before bedtime, which might have affected nocturnal sleep. In turn, reduction in TST might have induced the increased daytime sleepiness. Moreover, during MSLT, the use of a portable, at-home polysomnography-recording device in the above project forced the operator to program the computer to end the test 20 min after the beginning of recording regardless of sleep onset. Therefore the participants did not sleep long enough to progress to rapid eye movement (REM) sleep, which made comparison of sleep stages between naps before and during Ramadan less accurate. Given this proposed alteration in the circadian pattern of body temperature, we might also expect to find a change in the circadian secretion of melatonin. Melatonin is considered to be one of the best markers for circadian rhythm disruption.5 The circadian rhythm of melatonin secretion has not yet been investigated systematically under controlled conditions at the beginning and end of Ramadan to evaluate possible changes over time and whether adaptation occurs by the end of the month. Therefore, the present project was designed to examine the effect of Islamic fasting on sleep architecture, daytime sleepiness and the circadian pattern of melatonin level by using polysomnography (PSG) and the MSLT, along with other laboratory and subjective measures, during the first and third weeks of Ramadan (R1 and R3). In contrast to Rocky’s papers, the dinner meal in the present study was given 3 h before bedtime to control the possible effect of late meals on nocturnal sleep and circadian rhythm.

MATERIALS AND METHODS This observational study with repeated measures in a non-random sample of volunteers was approved by the Ethics Committee of the College of Medicine at King Saud University. The study was conducted during the month preceding Ramadan (Shaban) and the month of Ramadan in the year 1423 Hijra (between 24 October

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and 29 November 2002). During that period, fasting for Ramadan commenced at around 04:45–05:00 and breakfast was eaten at around 17:00–17:15.

Study group Eight healthy, Muslim volunteers who were not taking any regular medications and who do not drink alcohol participated in the study after giving their informed consent. Mean age was 31.8 ± 2 years and body mass index (BMI) was 25 ± 2.2. Additional exclusion criteria were sleep complaints, smoking, and/or addiction to caffeinated beverages. Before enrolment in the study, each volunteer received a medical check-up and a data form including demographic and sleep habits information was completed. All selected participants had fixed daytime working hours and a regular sleep-wake schedule during weekdays; they also had the same type of work, tasks and working hours before and during Ramadan.

Study protocol Participants were asked to complete a daily sleep diary when not in the Sleep Disorders Center (SDC). TST, nap duration, wake-up time and bedtime for study days (baseline and Ramadan) not in the SDC were calculated on a daily basis and the means were used in our analysis. Subjective sleepiness was assessed using the Epworth Sleepiness Scale (ESS).6 Participants reported to the SDC at King Khalid University Hospital (KKUH) at 16:00 on four occasions, spending approximately 24 h in the SDC on each occasion: 1 Initial visit for medical check-up and adaptation to the environment. 2 Baseline, or BL for PSG and an MSLT the next day. 3 During R1 for PSG and MSLT. 4 During R3 for PSG and MSLT. When in the SDC, participants took three meals per day with fixed caloric values and fixed proportions of carbohydrate, fat and protein based on their ideal body weights at the beginning of the study. Food items containing large amounts of 5-hyroxytryptamine were avoided on the study nights and days. At BL, dinner was served at 20:00, breakfast at 07:45 and lunch at 12:00. During Ramadan, breakfast was served at sunset around 17:00–17:15, dinner at 21:00 and a predawn meal (Suhur) at 04:30. Body weight and body fat were measured for each participant at every SDC visit. Serum glucose level was estimated at 15:00 on study days.

Sleep and Biological Rhythms 2004; 2: 135–143

Ramadan Fasting and Sleep

Body fat measurement FUTREX-5000 Analyzers (FUTREX, Gaithersburg, MD, USA) were used to determine body fat composition. The FUTREX-5000 emits near-infrared light into the body at very precise frequencies (938 nm and 948 nm) at which body fat absorbs the light and lean body mass reflects the light. The validity of this method has been previously documented.7 The measurement was taken at the midpoint of each participant’s dominant bicep.

Polysomnography Overnight sleep studies with PSG were performed in the SDC. Alice 4 (Respironics Inc., Murrysville, PA, USA) diagnostic equipment was used for data acquisition and the data were then downloaded to an IBM PC. A trained technician connected the participants to the monitor (as per the standard hook-up process) and stayed in the SDC throughout the study, monitoring the recording in the control room. Before Ramadan, PSG recording started at midnight (00:00) and ended at 07:30. During Ramadan, PSG recording started at 00:00 and continued until the participants were woken up at 04:30 for Suhur; PSG was then resumed at 05:00– 05:30 and participants were allowed to sleep until 08:00. Participants were asked to avoid any napping during the SDC days. During PSG recording, light intensity was maintained