What is the effect of intermittent fasting on sleep, if any?

The 2018 review {1} was quite inconclusive, except for REM sleep in the case of diurnal intermittent fasting:

The impact of diurnal intermittent fasting (IF) on circadian rhythm, sleep, and daytime sleepiness is an exciting topic that deserves future research. Earlier studies have suggested that diurnal IF during Ramadan causes a delay in the circadian rhythm of core body temperature and hormonal secretion. However, more recent studies controlling for lifestyle changes that may influence circadian rhythm showed no effects of diurnal IF on the circadian rhythm. [...] The only consistent change in all studies that assessed sleep architecture during diurnal IF is a decrease in the amount of REM sleep.

I wonder if there exists more recent and more conclusive studies on the effect of intermittent fasting on sleep.


  • {1} Almeneessier, Aljohara S, and Ahmed S BaHammam. “How does diurnal intermittent fasting impact sleep, daytime sleepiness, and markers of the biological clock? Current insights.” Nature and science of sleep vol. 10 439-452. 7 Dec. 2018, doi:10.2147/NSS.S165637 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6292409/
  • As you might have noticed from the authors' affiliation, this kind of q generally gets asked in Islamic countries... FWTW it's not a high-priority research topic elsewhere, so while I've upvoted your q (so it doesn't get auto-deleted), I'm not holding my breath for groundbreaking research...
    – Fizz
    Jan 5 '21 at 15:53
  • @Fizz thank you, a fair amount of research in non-islamic countries as well, e.g. twitter.com/davidasinclair/status/1067956822852726784?lang=en but yes for humans being in an islamic country helps a lot indeed. Jan 5 '21 at 22:47
  • There's a difference between caloric restriction and "intermittent fasting". You can actually end up eating more by the latter method. arabamerica.com/…
    – Fizz
    Jan 6 '21 at 0:44
  • @Fizz look at the second row in the tweet -> time restricted feeding. Jan 6 '21 at 0:47
  • Clearly "intermittent fasting" can have different meanings. Your 1st quoted article says that. The 2nd paper (in Science) defines it more narrowly "no or few calories are consumed for periods of time that range from one to several days, followed by AL feeding on the remaining days". People don't even do that for Ramadan, as far as I know (they only fast from dawn to sunset).
    – Fizz
    Jan 6 '21 at 1:04

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