Annals of Thoracic Medicine Official publication of the Saudi Thoracic Society, affiliated to King Saud University
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Year : 2018  |  Volume : 13  |  Issue : 1  |  Page : 48-54

The effects of diurnal intermittent fasting on the wake-promoting neurotransmitter orexin-A

1 Department of Family Medicine, College of Medicine, King Saud University, Riyadh, Saudi Arabia
2 Department of Physiology, College of Medicine, King Saud University, Riyadh, Saudi Arabia
3 King Abdulaziz and His Companions Foundation for Giftedness and Creativity, Manarat Al Riyadh School, Riyadh, Saudi Arabia
4 University Sleep Disorders Center, College of Medicine, King Saud University, Riyadh, Saudi Arabia

Correspondence Address:
Prof. Ahmed S BaHammam
University Sleep Disorders Center, College of Medicine, King Saud University, Box: 225503, Riyadh 11324
Saudi Arabia
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/atm.ATM_181_17

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BACKGROUND: Food restriction has been demonstrated to increase the alertness in different species and to increase the levels of the wake-promoting neurotransmitter orexin. We hypothesized that diurnal intermittent fasting (DIF) increases orexin-A levels during fasting. Therefore, we conducted this study to assess the effects of DIF, during the month of Ramadan, on orexin, while controlling for lifestyle changes that may accompany Ramadan such as sleep duration, bedtime and wake time, energy expenditure, light exposure, and food. METHODS: Eight young healthy volunteers (mean age, 25.4 ± 3.5 years) reported to the laboratory on three occasions: (1) 4 weeks before Ramadan while performing DIF for 1 week outside the month of Ramadan (fasting outside Ramadan); (2) 1 week before Ramadan (nonfasting baseline) (BL); and (3) during the 2nd week of Ramadan while performing DIF (Ramadan). Plasma levels of orexin-A were measured using an enzyme immunoassay five times at 22:00, 02:00, 04:00, 06:00, and 11:00. Caloric intake, light exposure, and sleep schedule were maintained during the participants' stays in the laboratory in the three study periods. RESULTS: Orexin-A levels increased in the daytime during fasting and decreased at night compared to BL. The differences in orexin-A levels between DIF and BL were significant at 06:00, 11:00, 22:00, and 02:00. CONCLUSIONS: DIF increases orexin-A levels in the plasma during fasting hours. This finding supports findings from animal studies showing that fasting increases alertness.

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