Ramadan fasting and its associated lifestyle changes have been linked to changes in sleep and daytime sleepiness. With a potential decrease in total sleep duration and fasting leading to food deprivation, it has been assumed that fasting in Ramadan makes us feel sleepier during the day. While subjectively this may seem true, a study done on this found no objective evidence for increased sleepiness during fasting. Research demonstrated shifts in sleep schedules, with delayed bedtimes and wake times, while other studies showed a reduction in total sleep time of about 1 hour from the normal baseline.

Managing your Eating Habits:

Ramadan for most of us is distinguished by an abrupt change in eating habits. Caloric intake increases at night, meal times are shifted, and cortisol and insulin levels become increased at night in Ramadan. Cortisol is important in times of stress, as too little of it leaves us feeling chronically fatigued. It plays a major role in nutrition in regulating energy and under stress it provides the body with glucose. But it also influences our appetite and cravings for high-calorie foods. It can be assumed that this shift in cortisol and insulin rhythms during Ramadan may in fact help by increasing our appetite for the meal before dawn (suhur). When chronically elevated however, cortisol can have harmful effects on weight, immune function, and chronic disease risk.

If higher levels of cortisol — and the resulting stimulation of appetite — are potentiated by our own poor food choices during Ramadan, deleterious changes on our health and sleep can result. Though most research confirms temporary weight loss for most (which typically returns after Ramadan).

Ramadan and REM sleep:

Researchers have long recognized that food deprivation has been shown to increase wakefulness and markedly reduce rapid eye movement sleep (REM), the phase of the sleep cycle which requires the most brain energy use and associated with dreaming. Graeme Mitchison and Francis Crick proposed in 1983 that the function of REM sleep “is to remove certain undesirable modes of interaction in networks of cells in the cerebral cortex”, a process they characterize as “unlearning”.

Does fasting in Ramadan then decrease our REM sleep? Most likely, it can, though it may not be across the board for everyone. Participants fasting in Ramadan in a study published in Sleep and Biological Rhythms were found to have a significant reduction in sleep latency (the duration it takes for a person to fall asleep) and REM sleep during the third week of Ramadan; otherwise, there was no significant effect on their sleep architecture. In other words, for a period during the month, they fell asleep faster, but had less REM sleep. 1 Another study confirmed that fasting only decreased REM sleep but had no other effect on other sleep stages.

In addition to the shift in our eating habits and mealtimes during Ramadan, other factors may affect our sleep pattern during Ramadan.  All of us have a built-in biological clock, which is essential in optimizing and regulating our sleep and other important biological processes, including hormonal and metabolic functions. These circadian rhythms take a major cue from sunlight and the day-night cycle to set this clock. Melatonin is a marker for the circadian rhythm, and signals our brains to know when it is time to sleep and when it is time to wake up. Normally, melatonin rises as the body prepares to sleep.

Ramadan, Sleep & Circadian Rhythm: 

When we then take into account that short-term fasting has also been reported to decrease melatonin levels, finding ways to strengthen our natural circadian clock in Ramadan becomes even more important.  We can strengthen our circadian clock sleep schedules by getting sunlight in the morning.  Exposure to sunlight in the early morning hours will reinforce our circadian rhythms, and can help counterbalance the effects of exposure to artificial light. Spending as little as 10 minutes outdoors in the morning will help push our circadian clock slightly earlier, more in sync with the solar day. This makes us feel more alert during the daytime and more ready for sleep at night. Reducing exposure to artificial light in the night and having a darkened bedroom is critical to sleeping well and maintaining a more natural circadian rhythm.