Table 1.
Study Characteristics of Included Papers on Ramadan.
| Citation | Study Conditions | N | Population Characteristics (Gender, Age, Body Mass Index (BMI)) | Cortisol Type | Cortisol Response | Melatonin Response |
|---|---|---|---|---|---|---|
| Al Rawi et al. 2020 * [31] |
Each subject’s values 1 week before Ramadan (T1) were compared to outcomes at the end of the fourth week of Ramadan (after completing 28 consecutive days of fasting, or T2). During Ramadan, study subjects abstained from all food and drink (including water) from dawn to sunset. The daily fasting duration during this study was approximately 15 h. Subjects were assessed in the late morning (11 a.m.–1 p.m.) |
57 | 17 females, 40 males Average age (years): 38.4 ± 11.2 years Average BMI: 29.9 kg/m2 |
Salivary | At the end of Ramadan, cortisol did not change compared to the levels assessed in the pre-fasting state (p-value “non-significant”). | At the end of the fasting month, serum melatonin was significantly decreased (p < 0.001) compared to baseline by 39%. |
| Almeneessier et al. 2017 [32] |
Participants reported to the Sleep Disorders Center (the laboratory) on four occasions: (1) adaptation, (2) 4 weeks before Ramadan while performing Islamic intermittent fasting for 1 week (fasting outside Ramadan (FOR)), (3) 1 week before Ramadan (non-fasting baseline (BL)), and (4) during the 2nd week of Ramadan while fasting (Ramadan). | 8 | 8 males Average age (years): 26.6 ± 4.9 Average BMI: 23.7 3.5 kg/m2. |
NA | NA | The melatonin levels followed the same circadian pattern during the three monitoring periods (BL, FOR, and Ramadan). Lower melatonin levels at 22:00 h were found during fasting compared to BL, with a significantly lower level for Ramadan versus BL (p < 0.05). No significant changes in the acro-phase of melatonin levels. |
| Bahijri et al. 2013 [33] |
Two intervention periods: Young, Ramadan practitioners were evaluated before and two weeks into the Ramadan. Blood samples were collected at 9.00 a.m. and 9.00 p.m. for measurements of metabolic parameters and cortisol. Saliva was collected every 4 h for 24 h, except when asleep, during both days of blood sampling. |
24 | 5 females, 19 males (one male dropped out) Average age (years): 23.1 ± 1.2 Average BMI (kg/m2): 24.6 ± 1.1 |
Salivary & Serum | Serum: Cortisol circadian rhythm was abolished during Ramadan (p = 0.068). Morning level was lower in Ramadan compared with the non-fasting month, but not significantly so (p = 0.06). Evening cortisol in Ramadan was significantly higher than during the non- fasting month (p = 0.008). This was reflected in a significantly lower a.m./p.m. cortisol ratio during Ramadan (p = 0.004) (Table 2). Salivary **: Ramadan resulted in obvious flattening of circadian cortisol secretion during the fasting month compared to the non- fasting month; with lower levels during mid-morning and higher levels in the evening and early morning. Had significantly decreased values in the evening during the non-fasting month (p = 0.018), but no such a decrease during the fasting month of Ramadan (p = 0.254). |
NA |
| Bogdan et al. 2001 [34] |
Two intervention periods: The volunteers were studied twice over a 24-h span: one week before Ramadan (control: end of December) and on the twenty-third day of Ramadan (Ramadan: end of January). | 10 | 10 males Average age (years): 34 ± 3.7 Average BMI (kg/m2): NR |
Serum | Serum cortisol levels rose in the afternoon, while the morning rise was apparently delayed. A higher morning peak and a sharper decline were observed during Ramadan. On the Ramadan test day, the cortisol rhythm was overtly biphasic, with an evident rise in the serum concentration starting at 12:00 h and a plateau between 16:00 h and 20:00 h, i.e., at the time of the first meal following the daytime fasting period. The morning cortisol peak was higher and steeper during Ramadan than on the control day. No significant increase in 24-h mean concentration of serum cortisol during Ramadan. |
The nocturnal peak of melatonin was diminished (p < 0.008) and may have been delayed. The melatonin pattern remained circadian during Ramadan. |
| Brini et al. 2019 [35] |
16 basketball players were randomly assigned to one of two training groups: a small-sided game group (GSSG; N. = 8) and a repeated sprint ability group (GRSA; N. = 8. The groups completed a 4-week training program during Ramadan (R, experimental month) and one month after Ramadan (AR, control month), interrupted by 15 days of total recovery, with a frequency of two sessions per week. Data was measured on six occasions: before R (P1), at the end of the second week of R (P2), at the end of R (P3), before the AR training period (P4), at the end of the second week AR (P5) and at the end of the AR training period (P6). Players reported to the laboratory at 09:30 h. Blood samples were collected from the seated athletes at least ~9 h after their last meal and at least 24 h after their last training session. |
16 | 16 males Average age (years): 23.4 ± 3.7 Average BMI (kg/m2): 22.6 ± 1.95 |
Plasma cortisol | GSSG + GRSA: Delta variation of cortisol showed a significant decrease in P3 compared to P1 in all subjects (p < 0.005) GSSG: Cortisol lower in P3 than it was in P1 (p = 0.036). GRSA: Cortisol was lower in P3 (75.1 +/− 51.3) compared to P1 (136 +/− 136 +/− 48.6) but this change was not significant. AR cortisol (1 month after Ramadan) was higher than cortisol during R after 2 and 4 weeks of training (DP2-P1 vs. DP5-P4: p = 0.0008 and DP3-P1 vs. DP6-P4: p < 0.0003). |
NA |
| Chennaoui et al. 2009 [36] |
In 8 middle-distance athletes a maximal aerobic velocity (MAV) test was performed 5 days before RF (day–5), and on days 7 and 21 of RF. The subjects observed RF and abstained from food and liquids from approximately 05:00 to 19:00 h for 30 days. The length of each fasting day was approximately 13 h. Samples collected 10 a.m.–11 a.m. |
8 | Participant sex unclear Average age (years): 25.0 ± 1.3 Average BMI (kg/m2): NR |
Salivary | Cortisol concentration increased only at day 7 (of RF). At day 7 and day 21 of RF, compared with day 5, and before the MAV test cortisol concentration was not statistically different (p = NS). | At the end of RF (P2), compared with before RF (P1), serum melatonin decreased (p < 0.05) |
| Dikensoy et al. 2009 [27] |
Thirty-six consecutive healthy women with uncomplicated pregnancies of 20 weeks or more, who were fasting during Ramadan, were included in the study group (group 1). The control group (group 2) consisted of 29 healthy pregnant women, who were not fasting during the study period. Maternal blood samples were obtained 1 week prior to Ramadan and on 20th days of fasting | 65 | Women (pregnant women, 36 fasting during Ramadan, 29 not fasting) Average age (years): NRAverage BMI (kg/m2): NR |
Serum | In the fasting group, the maternal serum cortisol levels on day 20 were significantly higher than the initial levels obtained 1 week prior to Ramadan (p < 0.05). | NA |
| Haouari et al. 2008 [37] |
Three intervention periods: Participants were examined on days 7 (D7) and 21 (D21) of Ramadan and one week before Ramadan as control (D0). The average duration of the fast was about 12 h Five millilitres of venous blood were drawn at 9:00, 13:00, 17:00, 21:00, 01:00, and 05:00 |
36 | 36 males Average age (years): 24 ± 1.6 Average BMI (kg/m2): average NR; 18.5 < BMI ≤ 24.9 |
Serum | The analysis of cortisol circadian showed a significant sinusoidal wave form of the three curves, both for the days of fasting (D7 and D21) and for the control day (D0) (p < 0.001), with a morning peak. Data showed no significant changes in the 24-h mean or in the amplitude and time of peak compared with the control day. However, results show that nocturnal cortisol levels during Ramadan were higher than during the control period (p < 0.01) at midnight on both D7 and D21. Curve of D7 showed a very slight advance, by one hour and 18 min accompanied by a remarkable decrease (p < 0.001) in the variability during the 24 h. |
NA |
| Vasaghi-Gharamaleki et al., 2014 [38] | Cross-sectional study Saliva was collected 2 weeks before the beginning of Ramadan (BR), during the first week (R1), middle (R2), the last week (R3) of Ramadan and 3 weeks after Ramadan (AR). Collection during 8 a.m.–9 a.m., no measure of evening cortisol. |
30 | 30 males Average age (years): NR; Age range: 30–76 years Average BMI (kg/m2): NR |
Salivary | Morning cortisol concentration and output significantly decreased compared to baseline in R1, R2, R3 and AR. Decrease in saliva cortisol level lasted 3 weeks after Ramadan (p < 0.05) | |
| Zangeneh et al. 2015 [28] |
A total of 40 women who were aged 20–40 years and known cases of PCOS and had no other medical diseases were included in the study. They were divided into two groups as follows: (i) study group (n = 20) who participated in Ramadan fasting and (ii) control group (n = 20) who did not participate in fasting. Variables were evaluated before and after Ramadan |
40 | 40 females with PCOS Average age (years): Ramadan fasting: 29.40 ± 4.60 Non fasting: 28.80 ± 3.86 Average BMI (kg/m2): average NR; 18.5 < BMI ≤ 24.9 |
Serum | Cortisol hormone concentration decreased in the fasting group (p = 0.049). | NA |
* Females exempt from fasting during menstruation; **: samples collected at different times of day; NR: not reported. PCOS: polycystic ovarian syndrome. DIF: diurnal intermittent fasting.