For many of us, work often competes for time with sleep – which is why many of us look forward to the weekend for a chance to “catch up” on sleep. But how much sleep is lost on days when we work? Our latest research shows that we get about 30 minutes less sleep than we would ideally need on each night of the working week.
We followed 100 people aged from 60 to 71 over two years, covering their transition into retirement. We measured their sleep on three separate occasions, with one year in between, and compared the sleep habits while they were working against when – and for how long – they slept after retirement.
After retirement, we found that every day was like a weekend – at least when it came to how long people slept for. Sleep duration increased, but only on weekdays, from 6.5 to seven hours a night on average. This meant retired people got about an equal amount of sleep every night of the week.
The amount of sleep people tended to get on their weekends while still in work seemed to be their preferred sleep duration, rather than “catch-up” sleep. If weekend sleep was prolonged to compensate for the working week’s sleep loss, we would have expected a drop after retirement (when there’s no sleep loss to compensate for) – but we this wasn’t the case.
Given that participants’ weekend sleep was their preferred sleep duration, weekend lie-ins will not compensate for sleep lost on weekdays while working. This means that our study participants had chronic partial sleep deprivation when they were working, of about 2.5 hours each week.
While adults are recommended to get at least seven hours per night for optimal health, sleep needs vary both between people and as we age. We need less sleep when we are older than when we are younger.
Different people need different amounts of sleep, which makes it hard to estimate what constitutes “too little” sleep for any given individual, but other studies have in experiments found that getting only six to seven hours of sleep affects attention and reaction time negatively compared to getting eight to nine hours of shuteye. This performance drop remained, even after getting a full night’s sleep three days in a row.
Partial sleep deprivation as a result of work can continue for years, which is why the accumulated effects needs to be considered. Sleeping less than seven hours on a regular basis is related to increased risk for various health conditions, including diabetes, stroke and depression. It’s also associated with impaired immune system function, as well as increased risk of accidents.
Social jetlag
Not only did sleep duration change with retirement, but people also went to bed later and woke later. Getting rid of the alarm clock seemed to be what drove the increase, as retired people went to bed about half an hour later and woke up an hour later on average during weekdays compared to when they were working.
Going to bed in time to get plenty of sleep before getting up for work is not always easy – especially for the majority of the population who have a late “biological clock”. This means they naturally prefer to go to sleep later and wake up later than people with an early biological clock.
Those with a late biological clock also have a tendency to postpone their bed and wake times on weekends more than others, which unfortunately sets their biological clock even later – making it hard to go to bed early on Sunday and even harder wake up early on Monday morning.
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When our biological clock is out of sync with the social clock (which is the timetable imposed on us by society) it can result in “social jetlag”. Social jetlag acts a bit like regular jetlag, and can make us feel down and tired. It’s also associated with higher risk for metabolic disorders and depressive symptoms.
Longer and more stable sleep across the week could, at least partly, explain why so many people experience improved mental health and drastically lower levels of fatigue after retirement.
But even though sleep patterns became more stable after retirement, people still went to bed and woke up around half an hour later on weekends compared to weekdays. This hints that other social factors – such as visiting with friends – also affect when and how much we sleep.
We also found that retired participants with a full-time working partner changed their sleep timing to a smaller extent than the rest, highlighting that sleep is social, as opposed to a purely individual phenomenon.
But there are some things you can do yourself to adjust your sleep patterns more to work and avoid “social jetlag” on Monday morning, including making sure you get plenty of daylight in the mornings. Morning light pushes our biological clock backwards, making it easier to fall asleep at night. However, the opposite is also true, so bright light should be avoided in the evenings and bedrooms should be dark.
It also helps to prioritise your sleep and keep a more regular sleep schedule, even on weekends. Allow yourself some extra time in bed on weekend mornings if you need it, but try to avoid throwing your weekend sleep schedule off too much in order to stay away from the vicious cycle of sleep loss and social jetlag.
That being said, our study suggests that work generates sleep loss and hinders people from sleeping in line with their natural rhythm. But just as later school start times are an effective way to improve sleep in adolescents, later (or flexible) start times at work could potentially have the same effect for working people – and may mean people won’t have to wait until retirement to get enough sleep.
Johanna Garefelt receives funding from the Swedish Council for Health, Working life and Welfare (Grant numbers: 2012-1743, 2017-00099).