Table 1.

A summary of the studies that objectively assessed changes in the circadian pattern of body temperature during diurnal intermittent fasting for Ramadan

Study	Study population	Study design	Assessment tool	Study setting	Findings	Study details
Roky et al25	8 healthy young adults (age: 20–28 years) Location: Morocco	Case crossover study with repeated measures	Rectal thermistor probe for at least 24 hours	Monitoring at home Controlled for meal composition and time, as well as bedtime and rising time	Delay in acrophase and bathyphase	The participants were of the intermediate chronotype as determined by the Morningness-Eveningness Questionnaire Dinner was served 1 hour before bedtime during Ramadan and 3 hours before bedtime at baseline No objective assessment of prior sleep pattern
Roky et al26	10 healthy young adults (age: 20–28 years) Location: Morocco	Case crossover study with repeated measures	High-precision medical oral thermometer at 09:00, 11:00, 13:00, 16:00, 20:00, and 23:00	Monitoring at home Controlled for meal composition and time, and bed and rise time	Reversal of circadian pattern of temperature	Subjects were of the intermediate chronotype as determined by the Morningness-Eveningness Questionnaire Sleep duration was 1 hour shorter during Ramadan than at baseline No objective assessment of prior sleep pattern
BaHammam et al30	8 healthy young adults (age: 31.8±2 years) Location: Saudi Arabia	Case crossover study with repeated measures	High-precision medical oral thermometer at 08:00, 16:00, and 00:00	Monitoring in the laboratory Controlled for meal composition	No change	No objective assessment of prior sleep pattern Subjects stayed in the laboratory during monitoring
BaHammam et al24	6 healthy young adults with delayed sleep phase disorder (age: 18–24 years) Location: Saudi Arabia	Case crossover study with repeated measures	SenseWear Pro Armband™ that measures proximal skin temperature during the last week of Shaban and the first 2 weeks of Ramadan	Free-living environment	Further delay in temperature acrophase	Subjects belonged to the evening chronotype Sleep patterns were monitored for 2 weeks prior to the study by using sleep diaries (no objective assessment) Sleep/wake schedule and sleep duration during the study were assessed objectively via armband Participants lived in an unconstrained environment during the study