Recent Scientific Discoveries About Sleep (2018-2019)

1Restorative function of sleep is nuclear maintenance

Recent animal experiment demonstrated that each single neuron requires sleep in order to perform nuclear maintenance. During wakefulness chromosome dynamics are low, and DNA damage consistently accumulates. Sleep increases chromosome dynamics and enables the recovery from DNA damage accumulated in the brain during wakefulness1.


2Sleep deprivation accelerates Alzheimer's disease

Exactly what causes neuronal degeneration in Alzheimer's disease is still a mystery. However, researchers found that sleep has a direct protective effect from tau protein, a precursor of brains pathology in Alzheimer's disease2.

Insufficient sleep triggers accumulation of beta-amyloid proteins between neurons in the brain. Beta-amyloid are strongly implicated in Alzheimer’s disease. On the other hand, increased accumulation of beta-amyloid and tau proteins disrupt the sleep-wake cycle, thus forming a defective cycle3.

3Screen time in darkness before bedtime increases a risk for poor sleep

Reseachers found that night-time use of phones, tablets or laptops is consistently associated with poor sleep quality4. Pre-sleep device use is particularly risky if the activity takes place in the dark.

4Sleep duration: neither too much nor too little

So far, seven hours are still considered the magic number for sleep. People who sleep less than six hours a night are at increased risk of cardiovascular disease compared with those who sleep 7-8 hours 5.

According to Japanese study, short and long daily sleep duration are risk factors for dementia and premature death. Researchers found that rates of dementia and all-cause mortality are greater in those who sleep less than 5 hours and more than 10, compared with those who sleep from 5 to 6.9 hours6.

5Physical activity in the evening does not cause sleep problems

Contrary to common belief, there is no reason to avoid exercising in the evening, an analysis of the scientific literature has revealed7. Even vigorous evening exercise is not detrimental to sleep quality8.

6We can learn new foreign words while asleep

Researchers showed that we can acquire the vocabulary of a new language during distinct phases of slow-wave sleep and that the sleep-learned vocabulary could be retrieved unconsciously following waking9.

7 Weekend sleep matters

There is evidence that long weekend sleep may compensate for lack of sleep during the week10.

8 Writing a "to-do" list at bedtime may aid in falling asleep

Researchers found that people who took five minutes to write down list of upcoming duties before bed fell asleep more quickly than people who recorded about completed tasks11.



  • 1. Zada D, Bronshtein I, Lerer-Goldshtein T, Garini Y, Appelbaum L. Sleep increases chromosome dynamics to enable reduction of accumulating DNA damage in single neurons. Nat Commun. 2019 Mar 5;10(1):895. PubMed
  • 2. Holth JK, Fritschi SK, Wang C, Pedersen NP, Cirrito JR, Mahan TE, Finn MB, Manis M, Geerling JC, Fuller PM, Lucey BP, Holtzman DM. The sleep-wake cycle regulates brain interstitial fluid tau in mice and CSF tau in humans. Science. 2019 Feb 22;363(6429):880-884. PubMed
  • 3. Ahmadian N, Hejazi S, Mahmoudi J, Talebi M. Tau Pathology of Alzheimer Disease: Possible Role of Sleep Deprivation. Basic ClinNeurosci. 2018 Sep-Oct;9(5):307-316
  • 4. Michael O. Mireku, Mary M. Barker, Julian Mutz, Iroise Dumontheil, Michael S.C. Thomas, Martin Röösli, Paul Elliott, Mireille B. Toledano. Night-time screen-based media device use and adolescents' sleep and health-related quality of life. Environment International, 2019; 124: 66
  • 5. Dominguez F, Fuster V, Fernandez-Alvira JM, et al. Association of Sleep Duration and Quality With Subclinical Atherosclerosis. J Am CollCardiol. 2019 Jan 22;73(2):134-144.
  • 6. Ohara T, Honda T, Hata J, et al. Association Between Daily Sleep Duration and Risk of Dementia and Mortality in a Japanese Community. J Am Geriatr Soc. 2018 Oct;66(10):1911-1918.
  • 7. Jan Stutz, Remo Eiholzer, Christina M. Spengler. Effects of Evening Exercise on Sleep in Healthy Participants: A Systematic Review and Meta-Analysis. Sports Medicine, 2018
  • 8. Robey E, Dawson B, Halson S, Gregson W, Goodman C, Eastwood P. Sleep quantity and quality in elite youth soccer players: a pilot study.Eur J Sport Sci. 2014;14(5):410-7.
  • 9. Züst MA, Ruch S, Wiest R, Henke K. Implicit Vocabulary Learning during Sleep Is Bound to Slow-Wave Peaks. Curr Biol. 2019 Feb 18;29(4):541-553.e7
  • 10. Akerstedt T, Ghilotti F, Grotta A. Sleep duration and mortality - Does weekend sleep matter? J Sleep Res. 2019 Feb;28(1):e12712
  • 11. Scullin MK, Krueger ML, Ballard HK, Pruett N, Bliwise DL. The effects of bedtime writing on difficulty falling asleep: A polysomnographic study comparing to-do lists and completed activity lists. J ExpPsychol Gen. 2018 Jan;147(1):139-146.

Published: March 14, 2019
Last updated: March 14, 2019

Written by eMedExpert staff


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