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Beauty sleep or not?

I had a terrible night last night. One of my patients who has been under my care for over a decade was admitted to a district hospital with life-threatening sepsis and has to have emergency surgery. It is touch and go if this patient will survive. I kept tossing and turning and rehearsing events that led up to their admission and kept wondering if anything could have been done to prevent the sepsis from progressing to a stage when it required surgery. The result is I had a very poor night’s sleep and feel terrible this morning; irritable, tired, groggy and foggy as if I have a hangover. What damage has this caused?

Photo by engin akyurt on Unsplash

It is clear that sleep is a physiological must; acute sleep deprivation is a major life-threatening stressor and kills. This is why it is used as a method of torture. Chronic sleep deprivation is also a stressor and also kills, only more slowly.

The paper by Eide and colleagues below shows how one night’s sleep deprivation impairs the brain’s clearance of a gadolinium tracer from most brain regions. Worryingly impaired cerebral clearance as a result of sleep deprivation was not compensated for by subsequent sleep. When it comes to sleep deprivation what is lost is lost. In other words, one night of total sleep deprivation impairs the molecular clearance from the human brain, which may not be reversible. It seems that we humans may not catch up on lost sleep and that chronic sleep deprivation may come at a cost. 

In parallel, the JAMA editorial below tells us how important sleep is for washing out and maintaining the health of the brain. It is becoming clear that the so-called glymphatic system of the brain is more critical than we realise. Its function is reduced in shift workers, people with a sedentary lifestyle and is also reduced following traumatic brain injury and in conditions associated with a raised intracranial pressure, in patients with sleep apnoea, obesity, hypertension, type 2 diabetes, cerebrovascular disease, cerebrovascular haemorrhage, ischaemic stroke, Alzheimer’s’ disease and obviously in sleep disruption or sleep deprivation.

I predict when it comes to brain health and good sleep hygiene, i.e. good quality sleep will be as important as exercise. Importantly they are not mutually exclusive; I sleep so much better on the days that I exercise. If you want to take brain health seriously you need your beauty sleep. 

Anthony Komaroff. Does Sleep Flush Wastes From the Brain? JAMA. 2021 May 17. doi: 10.1001/jama.2021.5631.

Eide et al. Sleep deprivation impairs molecular clearance from the human brain. Brain. 2021 Apr 12;144(3):863-874. doi: 10.1093/brain/awaa443.


It remains an enigma why human beings spend one-third of their life asleep. Experimental data suggest that sleep is required for clearance of waste products from brain metabolism. This has, however, never been verified in humans. The primary aim of the present study was to examine in vivo whether one night of total sleep deprivation affects molecular clearance from the human brain. Secondarily, we examined whether clearance was affected by subsequent sleep. Multiphase MRI with standardized T1 sequences was performed up to 48 h after intrathecal administration of the contrast agent gadobutrol (0.5 ml of 1 mmol/ml), which served as a tracer molecule. Using FreeSurfer software, we quantified tracer enrichment within 85 brain regions as percentage change from baseline of normalized T1 signals. The cerebral tracer enrichment was compared between two cohorts of individuals; one cohort (n = 7) underwent total sleep deprivation from Day 1 to Day 2 (sleep deprivation group) while an age and gender-matched control group (n = 17; sleep group) was allowed free sleep from Day 1 to Day 2. From Day 2 to 3 all individuals were allowed free sleep. The tracer enriched the brains of the two groups similarly. Sleep deprivation was the sole intervention.

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Disclaimer: Please note that the opinions expressed here are those of Professor Giovannoni and do not reflect the position of the Barts and The London School of Medicine and Dentistry nor Barts Health NHS Trust.

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