A Different Debt to Pay

Eradication of existing ‘bad’ debt is one of the pillars of living in a financially stable fashion. This is surely not news to many of you. In addition to loans, credit cards or mortgages, there’s another debt that most of us owe: sleep debt. Again, it’s probably not an earth-shattering revelation that sleep is vitally important for you. Building up sleep debt makes us feel terrible, yet we persistently ignore this other arrears. What are the knock on effects of allowing this somnolescent liability to accrue? 

Putting a shift in

In the vernacular, ‘putting a shift in’ is seen as an almost noble effort. It conjures up images of hard graft, perseverance through abhorrent conditions or toiling until exhaustion. Despite this exalted idiom, the existing evidence would suggest that shift work is rather bad for you. At the coalface of the NHS, there’s shift work aplenty. Amongst many other sequelae, shift work leads to a reduction in sleep, which is unsurprisingly more pronounced after working night shifts1.

Shift workers lose up to two hours of sleep per day1. In a year that’s nearly five hundred hours of sleep debt! It may not sound like a great loss, but performance is already impaired after missing out on two hours of sleep2. The effect snowballs too; performance declines progressively as sleep debt accumulates2

Around 50% of ‘normal’ day time workers will cut back on sleep in favour of other activities. For shift workers the number rises to between 60-70%3. The majority of those who are already behind on sleep are more likely to cut it back even further. It’s not something one ‘gets used to’ either; very few adapt to shift work due to the way our intrinsic circadian systems function4.

It’s not just that the quantity of sleep is reduced in shift workers, their quality of sleep is also poorer1. There are reductions in both deep sleep (refreshing/recharging) and REM sleep (learning and emotional regulation). Shift work is comparable to working in the UK and having your rest days in San Francisco1. Night shifts seem more akin to having rest days Down Under. Unsurprisingly, the fatigue associated with (night) shift work affects the psychological and physical wellbeing of the majority who undertake it2


We’ve all experienced the effect of tiredness on our ability to work. The hazy, foggy nature of incoming signals, the sluggish processing speed, the delayed, malfunctioning output. It’s certainly not enjoyable, though has even broader consequences. 

In terms of functioning, those doing shift work have a greater incidence of poor memory and poor performance compared to day workers. Worse still, they over-estimate their own capability4. Not only are you performing badly but you don’t even recognise it either! With worsening alertness and vigilance comes a four-fold increase in errors4. Reaction time is slowed: after sixteen hours awake it’s equivalent to a blood alcohol level at the legal drink/drive limit5

This unsurprisingly manifests as an increased risk of road traffic collisions driving home – 57% of surveyed doctors described an accident or near-miss travelling home from nights shifts2, 5. If this litany of fatigue-induced cognitive deficits isn’t enough, shift workers suffer from increased rates of mood disorders, depression and anxiety too4


It’s not only your mind that takes a bashing from a build-up of sleep debt, your physical health is also in the firing line. Various body systems are affected, though perhaps none more so than your heart.

An increased activation of the body’s natural stress systems puts more strain on the heart, leading to a rise in blood pressure. The long-term effect of this is a 40% increase in cardiovascular disease risk1. This predominantly comes in the form of increased risk of heart attacks (23%), other coronary events (24-41%) and strokes (5%)6. Interestingly these risks remained when other factors such as socio-economic status, itself a risk factor for cardiovascular disease, were taken into account. 

The very nature of being tired induces an increased appetite for energy-dense foods, which are typically high in sugar (or other tasty-but-detrimental ingredients)4. Weight gain and obesity tends to follow. There are also suggestions, but not conclusive data, of associations between night shifts and type two diabetes, metabolic syndrome, ulcers and other gastrointestinal disorders7, 8. For those starting a family, there is an increased risk of spontaneous abortion, premature birth and low birth weight1.

There may be some association between shift work, sleep debt and cancer. The strongest link appears to be between night shifts and an increased risk of breast cancer9. The relationship with other specific cancers, and indeed cancer as an over-arching disease, is less clear.

Unsurprisingly the plethora of detrimental effects listed above have added social consequences. Shift workers demonstrate increased rates of divorce and their children tend to underperform in school4. One study showed that other people are less inclined to socialise with individuals who had gotten insufficient sleep10. Furthermore, when sleep-restricted, participants were perceived as less attractive and less healthy.

Payment plan

Financial debt is rarely something that can be paid of in one fell swoop. We chip away at it each month, reducing it little-and-often until it’s gone. Similarly, those days, weeks, months or even years of sub-optimal sleep are unlikely to be corrected with one epic snooze. It’s time to make changes in order to repay this debt. 

A number of you probably know what to do to improve your sleep quality. ‘Sleep hygiene’ is a relatively popular topic. There are a whole host of resources on how to improve sleep, including those from the NHS, Sleep Foundation and Sleep Council. For those engaged in (night) shift work the best resource we found was this one. As you can see, there are a plethora of changes you can make to improve your sleep. We’re not suggesting that you make all the changes in one go. It’s not sustainable. You might manage a few days or even a week, but long-term you’ll slip back into the same old routine. Instead, pick one or two and start with those. 

The MedFI challenge for you then, dear reader, is to start paying off your sleep debt. Let us know how it goes!


Mr. MedFI


1 – JM Harrington. Health effects of shift work and extended hours of work. J Occup Environ Med. 2001; 58(1). Available here.
2 – H McKenna and M Wilkes. Optimising sleep for nights. BMJ 2018; 360. Available here.
3 – C Williams. Work-life balance of shift workers. Statistics Canada, Perspectives. 2008; 75(1): 5-16. Available here.
4 – C Harvey. Working nights: side effects and coping mechanisms. AQNB Productions. 2017. Available here.
5 – M Farquhar. Night shifts. Don’t Forget the Bubbles. 2017. Available here.
6 – MV Vyas et al. Shift work and vascular events: systematic review and meta-analysis. BMJ. 2012; 345. Available here.
7 – M Farquhar. Fifteen-minute consultation: problems in the healthy paediatrician – managing the effects of shift work on your health. Arch Dis Child Educ Pract Ed. 2017; 102: 127–132. Available here.
8 – Sleep Foundation. Living & coping with shift work disorder. Available here.
9 – X-S Wang et al. Shift work and chronic disease: the epidemiological evidence. Occup Med (Lond). 2011 Mar; 61(2): 78–89. Available here.
10 – T Sundelin et al. Negative effects of restricted sleep on facial appearance and social appeal. R Soc Open Sci. 2017 May; 4(5): 160918. Available here.

3 thoughts on “A Different Debt to Pay

  1. How interesting and although obvious- I hadn’t really thought about it longer term until now. When I was much younger I used to sign up for weekend shifts & even when older covering out of hours IT stuff. Whilst it was great to have the extra cash, the unknown if the phone went off really bit into “freetime”, and then those moments when it went off at 3am were the worse. After about 2 years, I gave it up, and the freedom and peace it gave me was much better than the actual money. Sleep it seems cannot just be bought- it has to be acquired on a daily basis without interruption.


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