Intended for healthcare professionals

Feature Christmas 2017: Time and Place

Things that go BONG! in the night

BMJ 2017; 359 doi: (Published 07 December 2017) Cite this as: BMJ 2017;359:j5615
  1. Michael Farquhar, consultant in sleep medicine,
  2. Kirandeep van den Eshof, chief sleep physiologist
  1. Evelina London Children’s Hospital, Guy’s and St Thomas’ NHS Foundation Trust, London, UK
  2. Correspondence to: M Farquhar michael.farquhar{at}

Disrupted sleep studies caused by Big Ben serve as a reminder of the importance of environment in getting a good night’s sleep, say Michael Farquhar and Kirandeep van den Eshof

At midday on 21 August 2017, Big Ben, the bell at the heart of the great clock of the Houses of Parliament in London chimed 12 times and then fell silent. If all goes to plan Big Ben will not “bong” again until 2021, allowing essential repair and conservation work to be carried out. Its silencing was controversial, attracting even the prime minister’s concern. Across the Thames, however, at St Thomas’ Hospital we greeted the silence with enthusiasm.

The Evelina London Children’s Hospital Sleep Centre sits within St Thomas’ original pavilions. We carry out over 200 polysomnographies each year, enabling detailed analysis of children’s sleep to aid assessment and management of sleep difficulties.1 Even relatively minor factors can affect sleep quality. Polysomnography detects subtle disruptions to sleep that, cumulatively, can have major consequences.

Clearly audible throughout St Thomas’ Hospital, Big Ben has chimed a tune called the “Westminster Quarters” every 15 minutes, every day, for most of the past 158 years. A longer version of the tune is heard on the hour, along with the strikes for the hour, which are commonly referred to as bongs. As the bell tolls, polysomnographic arousals—sleep disruptions—are regularly seen in children asleep in our centre, particularly at midnight. We record these as “Big Ben arousals” (fig 1).

Fig 1
Fig 1

Example polysomnograph showing an arousal in sleep caused by the chimes of Big Ben at midnight

Arousals in sleep are common in everyone and can have multiple causes. The noise of the bell is one common reason given for why children (and their parents) attending our centre don’t sleep as well as they normally would.

Sleep studies in our department are attended by a trained sleep physiologist. Our sleep physiologists analyse arousals and exclude those that are clearly caused by external factors—such as Big Ben or snoring from the parent co-sleeping in the room—so that clinical decisions are not overly influenced by these. Exclusion of artefacts is a core skill for any sleep physiologist.

Quality sleep depends on a foundation of good sleep routine and habits plus a favourable sleep environment. Environmental factors—how light, temperature, comfort, and noise can affect how good our bedrooms are for sleep—can easily be overlooked, particularly in the context of other complex medical problems. Many children seen in our clinic have neurodevelopmental conditions such as autism and can be very sensitive to environmental stimuli. But this isn’t unique to those with neurodevelopmental conditions.

In a survey of factors that affect sleep quality, 25% of respondents cited noise as the most common problem, second only to an uncomfortable bed.2 Most of us don’t sleep within earshot of Big Ben, but many of us sleep where the outside world can noisily intrude into our bedrooms as we slumber. This is especially true in hospitals, where sleep for inpatients can often be very difficult.3 In 2015 our trust implemented measures to improve sleep quality of every inpatient, with a focus on reducing night time ward noise.

Environmental factors, including noise, should be evaluated as part of a sleep history, and noise reduction strategies, such as earplugs or use of white noise, should be actively considered as part of overall plans to improve sleep quality. Emphasis on, and education about, simple measures to achieve good sleep quality can make big differences.4

Getting enough good quality sleep is essential for every aspect of physical and mental health. Even if we think we have slept long enough, poor quality sleep will make us feel tired and unrefreshed the next day. We can then feel slow and sluggish and are more likely to be irritable, impatient, and to find even simple tasks difficult. Over time, even mild chronic sleep deprivation can increase lifetime risks of conditions such as heart disease, stroke, and hypertension.5

Big Ben arousals remind us all to improve our own sleep environments and to think about the simple things that can help us sleep better every night. Our newly expanded Evelina London Sleep Centre, due to open in 2018, will have better soundproofing, ready for Big Ben’s triumphant return in 2021. In the meantime, we hope the only thing disturbing children’s sleep on Christmas Eve is the sound of Santa’s reindeer landing on the roof.


We thank the children and families who have attended our sleep laboratory over the past five years and had their sleep disrupted by Big Ben, and we thank our team of children’s sleep physiologists who have faithfully recorded the impact of Big Ben’s bongs.


  • All authors have completed the Unified Competing Interest form (available on request from MF) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years, no other relationships or activities that could appear to have influenced the submitted work.

  • MF affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned have been explained.

  • Provenance and peer review: Not commissioned; externally peer reviewed.


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