“Feeling anxious? Go to bed earlier: Getting more sleep really can calm the mind,” reports the Mail Online.
However, if you’re more of a "glass half-empty" sort of person, the headline could have read “feeling anxious affects your sleep” – which is an equally valid interpretation of the same results.
A study of 100 university students has found that shorter sleep and delayed ability to get to sleep are associated with repeated negative thoughts (RNT). RNT are unwanted, unhelpful and distressing thoughts that are repeated over and over again, such as “my life is pointless”.
Students filled in surveys assessing their sleep patterns, mood, anxiety levels and how often they experienced RNT. There was a clear correlation between poor sleep quality and RNT but the “direction of travel” is unclear. Does poor sleep lead to RNT or does RNT lead to poor sleep?
It’s plausible that lack of sleep might make negative thoughts or mood worse, as it does for concentration. Similarly, it’s easy to imagine that worrying about issues can stop someone sleeping well.
If you are troubled by persistent insomnia and unwelcome thoughts that you feel you cannot control, see your GP. Talking therapies such as cognitive behavioural therapy can often help with both of these issues.
Where did the story come from?
The study was carried out by researchers from Binghamton University, US. Sources of funding were not reported.
The study was published in the peer-reviewed medical journal Cognitive Therapy and Research.
The Mail Online accurately reported on the study (and somewhat unusually for the Mail, put a positive spin on the results), though it did not make it clear that the study was conducted on apparently healthy student volunteers. Similarly, it did not highlight the most important limitation of the study, the possibility of reverse causation or what is known in academic circles as “the chicken egg problem”.
The Mail also reported “a spate of studies [that] suggested getting between seven and eight hours is essential for good health”. This refers to separate research, which we have not appraised. Consequently, we cannot comment on the accuracy of these specific statements.
That said, there is a general consensus of expert opinion that persistent lack of sleep can be detrimental for both your physical and mental health.
What kind of research was this?
This was a cross-sectional study that aimed to see if the student responses to a variety of questionnaires indicated any association between repetitive negative thinking (RNT) and sleep. RNT describes when a person has distressing or worrying thoughts that are repeated over and over again and are difficult to control.
RNT occurs in a variety of mental illnesses, including generalised anxiety disorder, major depression, post-traumatic stress disorder (PTSD) and obsessive compulsive disorder (OCD). It can also occur in people who do not currently have a mental illness and generally causes increased feelings of anxiety and a lowering of mood. The researchers wanted to explore the relationship between RNT and a lack of sleep or delay in getting to sleep.
As this was a cross-sectional study, it cannot prove causation. That is, whether poor sleep causes RNT or RNT causes poor sleep. Both scenarios seem plausible.
What did the research involve?
The researchers recruited 100 US university students who had volunteered to participate in any research studies. They were on average 19 years old and 58% of them were female.
The students completed a variety of questionnaires assessing their levels of worry, thought patterns, sleep patterns and whether they were more of a morning or an evening person. This included the:
- Worry Domain Questionnaire (WDQ)
- Ruminative Response Scale of the Response Style Questionnaire (RRS)
- Obsessive Compulsive Inventory (OCI)
- Perseverative Thinking Questionnaire (PTQ)
- Positive and Negative Affective Schedule (PANAS)
- Negative Affect scale (PANAS-NA)
- Pittsburgh Sleep Quality Index (PSQI)
- Horne Ostberg Morningness-Eveningness Questionnaire (MEQ)
The researchers then performed statistical analyses to look for any associations between sleep and repetitive negative thinking from the answers to these questionnaires.
What were the basic results?
The main findings were:
- increased RNT was associated with shorter sleep and delayed sleep
- shorter sleep was associated with more rumination (repetitive thinking)
- delayed time getting to sleep was associated with more obsessive-compulsive symptoms
On average, the students:
- went to bed at 1am and got to sleep within 22 minutes
- slept for about seven hours
- were mostly “evening” types
- did not score highly overall for the symptoms on any of the questionnaires
How did the researchers interpret the results?
The conclusion reached by the researchers was that repetitive negative thinking “may be uniquely related to both sleep duration and timing”.
This study has found an association between shorter sleep and increased reported RNT.
However, there are a few points to bear in mind when considering how applicable the results of this study would be to the general population, people who have a mental illness or are particularly affected by RNT:
- due to the cross-sectional measure of sleep patterns at one point in time, we cannot tell whether lack of sleep, or delayed sleep, causes RNT or whether RNT causes sleep disturbance – both directions of effect are plausible
- none of the participants in the study were reported to be suffering from any mental illness or other conditions that may affect the level of RNT
- they were all young, adult students
- it could be argued that they may have been of a certain personality type to have been willing to complete seven extensive questionnaires
- sleep patterns of people in this particular age group who are at university are unlikely to be representative of the sleep patterns they will have at other times of their life
However, commonsense tells us that a lack of sleep is likely to make any negative thoughts or mood worse. Tips on how to get a better night’s sleep can be found here.
If you are suffering from unwanted, repetitive thoughts that are causing you distress, talk to a healthcare professional. There are a range of simple techniques that can help, in addition to more formal methods such as cognitive behavioural therapy.