Does having a 'sense of purpose' in life help you sleep better?

Monday July 10 2017

"Sense of purpose aids sleep, US scientists find," The Guardian reports on a new study that explored the relationship between having a sense of purpose in life and quality of sleep in older adults.

The study analysed data from 800 older adults with an average age of 80 in the US.

Researchers found that generally, having a greater sense of purpose in life was associated with better quality of sleep, as well as a decreased likelihood of sleep disorders such as sleep apnoea and restless leg syndrome

Although these are interesting findings, it's not possible to rule out the influence of other factors.

The fairly abstract concept of "sense of purpose" may be influenced by various health and lifestyle factors, such as levels of physical activity and mental health problems, and these may all in turn affect quality of sleep.

But this study wasn't able to pull out all of the intricacies of this complex relationship.

Problems with sleep are more common in the UK than most people realise, but there are proven ways to help combat insomnia.

As for having a "sense of purpose", research has shown that volunteering your time for a cause or charity you believe in can help improve your mental wellbeing.

Read more about how giving can improve your wellbeing

Where did the story come from?

The study was carried out by researchers from Northwestern University in the US, and was funded by the National Institute on Aging Grant Numbers and the Illinois Department of Health.

It was published in the peer-reviewed journal Sleep Science and Practice. It's available on an open access basis and is free to read online.

The UK media coverage around this research was generally balanced and well reported.

What kind of research was this?

This analysis of data from two cohort studies set out to explore the relationship between having a sense of purpose in life and quality of sleep.

Previous research has suggested that having a sense of purpose in life could protect against several negative health outcomes, one being sleep disturbances. Sleep disturbance is known to be more common among older adults.

Studies have also observed the prevalence of sleep disturbance to be higher among African Americans than white people. The researchers wanted to investigate this further.

Cohort studies are useful for looking at an association between an exposure and an outcome. But the study design means it isn't possible to fully rule out the influence of other confounding factors and prove that a purpose in life directly leads to better sleep.

What did the research involve?

The data sample for this analysis was taken from two ongoing Chicago-based cohort studies: the Minority Aging Research Study (MARS) and the Rush Memory and Aging Project (MAP).

MARS is a study of risk factors for cognitive decline that recruits older African Americans who haven't had a diagnosis of dementia.

MAP aims to look at the brain changes associated with ageing and cognitive decline. It recruited older adults of mostly white ethnicity (88%) without a diagnosis of dementia who agreed to annual clinical assessments, as well as brain autopsy after they died.

The analysis included 825 older adults with an average age of 79.

Purpose in life was measured at the start of the studies using a modified 10-item assessment derived from the Ryff and Keyes' Scales of Psychological Well-Being, a tool used to assess sense of purpose.

As part of the assessment, individuals were asked to respond to statements like "I feel good when I think of what I've done in the past and what I hope to do in the future", and "Some people wander aimlessly through life, but I am not one of them".

Participants used a five-point scale for their responses, ranging from 1 strongly disagree to 5 strongly agree. Higher scores were used to indicate higher levels of purpose in life.

Sleep quality and symptoms of potential sleep disorders were assessed using a 32-step questionnaire derived from the Pittsburgh Sleep Quality Index (PSQI), the Berlin Questionnaire, and the Mayo Sleep Questionnaire (MSQ). The questionnaire was given to participants at the end of each annual visit.

The PSQI assessed sleep quality, specifically looking at how long it takes to fall asleep, sleep duration, and how much you actually sleep during the night.

The Berlin questionnaire assessed risk of sleep apnoea, and the MSQ assessed the presence of restless leg syndrome and REM behaviour disorder, where dreams are acted out (for example, through sleepwalking or shouting out).

Sleep data was collected at baseline and follow-up points at the end of the first, second and third year.

The researchers analysed any links with purpose in life, adjusting for potential confounders like age, sex, race and years of education.

Changes in quality of sleep over the course of the two-year study were also taken into account.

What were the basic results?

  • Out of all the 825 respondents, at the beginning of the study 42% were at high risk of sleep apnoea, 23.6% were exhibiting symptoms of restless leg syndrome, and 7% had symptoms of REM behaviour disorder.
  • Higher levels of purpose in life were associated with better sleep quality. Over a one-year period, improved sleep quality was reported in people with a higher "purpose of life".
  • Increased levels of purpose in life were associated with a decreased risk of sleep apnoea (odds ratio [OR] 0.630, 95% confidence interval [CI] 0.454 to 0.875). This association continued during the first and second follow-up assessment.
  • Purpose in life wasn't significantly associated with symptoms of restless leg syndrome. But at year one of follow-up, it was associated with a decreased likelihood of having possible restless leg syndrome (OR 0.524, 95% CI 0.361 to 0.762).
  • Purpose in life wasn't significantly associated with REM behaviour disorder at baseline or years one, two and three of follow-up.

How did the researchers interpret the results?

The researchers concluded that, "In a biracial sample of over 800 older adults, the present findings provide support for the hypothesis that purpose in life is related to sleep quality, with indications that it could be a potentially useful clinical tool for assessing older adults."

They added: "We found that higher levels of purpose in life at baseline predicted better sleep quality at baseline, as well as increased change in sleep quality over a one-year period, a finding that is consistent with previous studies." 

Conclusion

This study explored the relationship between having a sense of purpose in life and sleep quality and sleep disorders.

Researchers found generally, having a greater sense of purpose in life was associated with better quality of sleep and a decreased likelihood of sleep disorders like sleep apnoea and restless leg syndrome.

The researchers suggest this may be down to people having better overall physical and mental health.

Although these are plausible hypotheses, there are a few points to note. As with the majority of cohort studies, it isn't possible to prove cause and effect and fully rule out the influence of other health, lifestyle and personal factors in the associations.

For example, having a healthy lifestyle can have an impact on quality of sleep. Drinking too much alcohol, smoking, not getting enough exercise, and mental health problems may reduce the chances of having a good night's sleep.

And it's difficult to know the exact impact of having less of a sense of purpose in life on sleep quality. This is a fairly abstract concept that may have various external influences this study wasn't able to fully explore.

The length of time a person has felt a particular way may also have an effect. For example, the effect on sleep may not be the same in someone who's felt they have no purpose in life for a long time compared with someone who's recently been under acute stress.

It would be interesting to conduct this study in young adults to see if the findings are similar. There may also be different possible influences on sleep, such as different dietary factors (like sugary drink consumption) or increased screen use, in other populations.

Learn about different ways to get a better night's sleep.

Analysis by Bazian
Edited by NHS Choices