Resolving to Sleep

We’re now 9 days into 2015 and people are already starting to break their New Year’s resolutions. However, according to a recent article in the Daily Mail, the only resolution you need to stick to is getting more sleep and the rest should be easy to keep. But is it really that simple?

What did the article say?

The bullet points at the beginning of the Daily Mail article highlighted that, of the 1000 people studied, “two thirds of those who slept well achieved their new year’s resolutions”, while 44% who slept poorly achieved theirs. Translated into relative risk, this means that people who get poor sleep are 1.7 times more likely to fail at their New Years resolutions than people who get good sleep. However, the article later clarified that actually only 60% of the good sleepers attained their goal, making the relative risk figure a less-impressive 1.4.

The article ends with some quotes from the lead author, Professor Richard Wiseman of the University of Hertfordshire, suggesting that lack of sleep decreases the energy available for willpower and indicating a causal relationship between sleep and goal attainment, “If they went to bed a bit earlier then it would make it easier to achieve their resolutions.”

What did the original source say?

One thing we emphasise over and over at Research the Headlines is to check if the article clearly points to the original source for a story. However, in a Guardian article written by Wiseman himself, it became clear that the figures reported in this article were from an unpublished survey that Wiseman had completed a month ago.

You can take part in a similar survey at his website. This survey asked you to rate your sleep and ability to keep your resolutions on the following scales:

If the survey reported in the Daily Mail and Guardian articles used the same questions, it is even less clear exactly what is going on with this study. Were “poor” and “very poor” sleep categories lumped together? What happened to data from people with uncertain sleep or resolution attainment? What is the difference between “yes” and “definitely yes”?

Indeed, a caption at the end of the Daily Mail article stated that “Around 80 per cent of Britons fail to stick to their New Year’s resolutions”. Given the 56% failure rate for poor sleepers and 40% failure rate for good sleepers reported above, this suggests that either the survey respondents are atypical of Britons, or that new year’s resolution attainment is truly dreadful for categories of sleep other than “good” or “poor”.

Does lack of sleep cause failed resolutions?

The idea that willpower is a resource that can be replenished by sleep or glucose has been soundly criticised, casting some doubt on the alleged mechanism for this effect. So what other reasons might there be for the association between sleep and goal attainment?

As emphasised in our recent article on causality, a correlation is not not always good evidence for a casual relationship between two things.  Perhaps a third variable is causing both poor sleep and poor adherence to resolutions? For example, stressful life events like a death in the family or losing your job can definitely cause lack of sleep and are also likely to make it harder to stick to resolutions.

The bottom line

So is more sleep going to help me keep my resolutions? The detrimental effects of poor sleep are widespread and well documented, so the benefits of getting better sleep probably outweigh the costs, even if there is no effect on your New Year’s resolutions.