Category: Sleep and dreaming

Morning people ("larks") are more punctual than "owls"

You’ve probably heard that sleep psychologists like to divide people up into those who function optimally in the morning, and those who come alive at night (but see also). The former, “larks”, tend to get up and go to bed earlier than “owls”. A new study asks whether larks also tend to be more punctual people than owls – surprisingly, this is the first time anyone has examined this link.

Laura Werner and her team waited as nearly 300 students arrived for their 8.15am morning lectures on 14 different courses at the University of Education in Heidelberg, Germany. The students’ time of arrival was noted and they were given surveys on personality, their chronotype (i.e. lark vs. owl), their punctuality in general, and their means of transport to university.

The students who were larks tended to arrive more punctually for their morning lectures. Other measures of personality, such as conscientiousness, had no association with lecture punctuality. As an owl myself, I thought it was a bit harsh to gauge punctuality with a morning lecture, but then the researchers did also ask the students about their general punctuality, and again chronotype was the key factor, explaining 12 per cent of the variance. Conscientiousness was only associated with self-reported punctuality when chronotype was omitted from the analysis.

The importance of chronotype was reduced once transport method was taken into account. Students arriving on foot or bike were generally later than those arriving by car or public transport, a result that will astonish British readers accustomed to traffic jams and trains with perfect records for being late.

As this is the first ever study to examine the links between being a lark or owl and being punctual, it’s obviously not the last word on the subject. We need more research in different contexts and with actual punctuality measured at different times of day. However, the new results do chime with past evidence that larks are more proactive people than owls.

Werner and her team ended on a self-deprecating note: “In our study based on lectures and university courses, we expect a lower commitment to punctuality compared to other types of appointment [come on profs, I’m sure your lectures aren’t that bad]. Punctuality may be therefore dependent on the situation, but nevertheless, morning people are expected to be punctual across different situations and appointments.”

_________________________________ ResearchBlogging.org

Werner, L., Geisler, J., & Randler, C. (2014). Morningness as a Personality Predictor of Punctuality Current Psychology, 34 (1), 130-139 DOI: 10.1007/s12144-014-9246-1

further reading
Early risers are more proactive than evening people
Owls get poorer school grades than larks
Creatures of the night – people who favour the evening score higher on Dark Triad personality traits

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest

Exposure to different forms of violence affects kids’ sleep differently

By guest blogger Jordan Gaines Lewis

If you need an accurate assessment of your emotional health, look no further than the quality of your sleep. Have an important test coming up? Giving a big talk to your company tomorrow morning? Chances are you’re not sleeping as well as you typically would.

While most kids have fewer of these worries than adults, some unfortunately have to deal with a different type of stressor—violence. Previous work has shown that kids exposed to violence report significant sleep disturbances compared to non-abused children. It’s thought that witnessing or experiencing a violent event causes increased vigilance due to the perception that one’s safety is at stake, resulting in disturbed sleep. Most of these studies, however, employed subjective (self-reported) sleep quality measures, which can be unreliable.

A study by Jim Spilbury and colleagues published last month in Sleep Medicine set out to clarify the association between violence and sleep quality in children by adopting both longitudinal and objective measures. The authors hypothesised that different forms of violence, such as being physically assaulted versus witnessing a homicide, would affect certain sleep characteristics differently.

The researchers recruited 46 children between the ages of 8 and 16 years from a community-based violence intervention program. Measures were taken at two time points: baseline (within 7 weeks of the violent incident) and after a 3-month follow-up.

At each time point, participants wore an actigraph for one week—a wristwatch-like device that uses movement to determine when individuals are asleep. Five measures of sleep disturbance were extracted from the actigraph: bedtime, sleep duration, sleep efficiency (percentage of time actually asleep while in bed), the amount of time awake at night after initial sleep onset, and sleep duration variability over the week.

Participants also completed two surveys: the Recent Exposure to Violence Scale (which assessed a range of violent events in the kids’ neighbourhood, school, and home over the past year), and a self-reported measure of lingering trauma after a stressful event.  A parent of each participant also reported on their child’s sleep quality.

The type of violence experienced by participants varied. Family violence was witnessed by 57 per cent of the children, community violence by 43 per cent, and 41 per cent had suffered physical assault themselves.

Two particular types of violence stood out to researchers in terms of their association with sleep disturbance. Controlling for relevant confounders (such as age, gender and family income), individuals who were physically assaulted had a shortened sleep duration (by 35 minutes on average), exhibited almost three times as much wake time after sleep onset, and 6 per cent lower sleep efficiency than kids who did not experience physical assault. These effects were also seen three months later at follow-up.

On the other hand, children who witnessed a homicide had twice as much wake time after sleep onset, greater night-to-night variability in sleep duration, and more self-reported sleep problems than kids who had not witnessed a homicide. These findings, however, did not persist at follow-up.

It’s not clear why different violent experiences are associated with different objectively- and subjectively-measured sleep outcomes. The researchers suggest that, perhaps, persistence of the sleep disturbance in those who were physically assaulted, as opposed to those who witnessed a homicide, reflects how the former may be perceived as more damaging to one’s personal sense of safety, resulting in greater vigilance and nighttime arousal.

Although this was only a pilot study, its implications for public health and awareness are extremely important. Significant research over the past decade suggests that disturbed sleep in children and adolescents is associated with elevated inflammation, increased prevalence of obesity, and behavioural problems, although the causal relationship between these variables and poor sleep quality is difficult to determine. Interestingly, the researchers found no relationship between parent-reported sleep quality and the participants’ actigraphy measures, suggesting that many parents may not be aware of their children’s sleep difficulties.

While addressing a child’s emotional needs after exposure to violence is clearly important, this study suggests that assessing physical health, such as objectively measuring sleep, is also necessary to assess one’s well-being. After all, disturbed sleep may tell a whole different story of which a parent—or a child, for that matter—may not even be aware.

_________________________________ ResearchBlogging.org

Spilsbury, J., Babineau, D., Frame, J., Juhas, K., & Rork, K. (2014). Association between children’s exposure to a violent event and objectively and subjectively measured sleep characteristics: a pilot longitudinal study Journal of Sleep Research, 23 (5), 585-594 DOI: 10.1111/jsr.12162

Post written by Jordan Gaines Lewis, a PhD student at Penn State College of Medicine studying sleep and obesity in adolescents. She blogs about neuroscience at Gaines, on Brains. Follow on Twitter @GainesOnBrains.

You’ve heard of "Owls" and "Larks", now sleep scientists propose two more chronotypes

For many years psychologists have divided people into two types based on their sleeping habits. There are Larks who rise early, feel sprightly in the morning, and retire to bed early; and Owls, who do the opposite, preferring to get up late and who come alive in the evening.

Have you ever thought that you don’t fit either pattern; that you’re neither a morning nor evening person? Even in good health, maybe you feel sluggish most of the time, or conversely, perhaps you feel high energy in the morning and evening. If so, you’ll relate to a new study published by Arcady Putilov and his colleagues at the Siberian Branch of the Russian Academy of Sciences.

The researchers invited 130 healthy people (54 men) to a sleep lab and kept them awake for just over 24 hours. The participants were asked to refrain from coffee and alcohol, and several times during their stay they filled out questionnaires about how wakeful or dozy they were feeling. They also answered questions about their sleep patterns and wakeful functioning during the preceding week.

By analysing the participants’ energy levels through the 24 period and their reports about their functioning during the previous week, Putilov and his team identified four distinct groups. Consistent with past research, there were Larks (29 of them), who showed higher energy levels on the first and second mornings at 9AM, but lower levels when tested at 9PM and midnight; and there were Owls (44 of them), who showed the opposite pattern. The Larks also reported rising earlier and going to bed earlier through the previous week, whereas the Owls showed the opposite pattern. There was an average two-hour difference between the sleep and wake cycles of these two groups.

The researchers also identified two further chronotypes. There was a “high energetic” group of 25 people who reported feeling relatively sprightly in both the morning and evening; and a “lethargic” group of 32 others, who described feeling relatively dozy in both the morning and evening. Unlike the Owls and Larks, these two groups didn’t show differences in terms of their time to bed and time of waking – their habits tended to lie mid-way between the Larks and Owls.

The researchers said their results support the idea of there being “four diurnal types, and each of these types can … be differentiated from any of three other types on self-scorings of alertness-sleepiness levels in the course of 24-hours sleep deprivation.”

We already have bird names for morning and evening people – Owls and Larks. Part of the title of this new paper is “A search for two further ‘bird species'”. I was hoping the authors might propose two new bird names for their high energy and lethargic categories, but sadly they don’t. What about Swift for the high energy category? I’m not sure about a lethargic bird. It’s over to you – any ideas? [Readers on Twitter have so far proposed Dodo and Pelican].

_________________________________ ResearchBlogging.org

Putilov, A., Donskaya, O., & Verevkin, E. (2015). How many diurnal types are there? A search for two further “bird species” Personality and Individual Differences, 72, 12-17 DOI: 10.1016/j.paid.2014.08.003

further reading
Owls get poorer school grades than larks
Early risers are more proactive than evening people

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

Does dreaming of exam failure affect your real-life chances of success?

Why do we dream? It’s still a scientific mystery. The “Threat Simulation Theory” proposes that we dream as a way to simulate real-life threats and prepare ourselves for dealing with them. “This simulation in an almost-real experiential world would train the brain to perceive dangers and rapidly face them within the safe condition of sleeping,” write the authors of a new paper that’s put the theory to the test.

Isabelle Arnulf and her colleagues reasoned that if dreams help simulate future threats, then students who dream about an important exam might expect to see some kind of advantage over students who don’t.

The researchers contacted thousands of first-year students at the end of the day that they sat a very important exam. Their performance would dictate whether they gained access to medical school. Just over 700 of the students agreed to participate and they completed a questionnaire about their dreams and sleep quality the previous evening, and any dreams they’d had about the exam over the course of the university term.

For the 44.1 per cent of the students who reported having a dream the night before their exam, most said they’d dreamt about the exam, and usually this dream featured some kind of problem such as not understanding questions, getting delayed en route or their pen not working. Looking back over the preceding term, 73.4 per cent of the students said they’d had a dream about the exam, with 87.5 per cent of these dreams featuring some kind of problem.

Next, the researchers gained access to the students’ exam results. The students who dreamt about the exam the night before gained better grades than those students who didn’t, and students who had dreamt about the exam at some point during the term achieved higher grades than students who did not report having any such dream.  The more exam dreams a student reported having during the term, the higher their grade tended to be.

These results appear to provide support for the Threat Simulation Theory of dreaming. Less consistent with the theory is the fact that the precise nature of the exam dreams was not related to exam grades. For example, students who dreamt of problems with the exam didn’t score higher grades than those who dreamt of success. However, it’s notable that the top five scorers on the exam all reported dreaming of exam problems, including being late and running out of time.

“As stated by some students, the immediate benefit of dreaming was the drive to address weaknesses in knowledge after awakening, which certainly provided an advantage,” the researchers said. “Additionally, the contrast between the horrible situations experienced in the dreams (appendicitis, lateness, impossibility of competing) and the the more casual reality (good health, appropriate timing and tools) the next morning may desensitise the students to anxiety, which can be reassuring and beneficial for competition.”

While these results are intriguing, we should interpret then with caution. It’s notable that other factors, besides dream content, had a far stronger relationship with students’ performance, such as past academic achievement and being male. Also, rather than dreams causing superior performance, there many be other factors influencing both dream recall and performance. Anxiety or sleep quality and duration would be obvious candidates, but in fact the researchers found no link between these factors and exam grades. A final issue of course is the unreliability of dream recall, especially considering the students were asked to think back over a whole term.

_________________________________ ResearchBlogging.org

Arnulf, I., Grosliere, L., Le Corvec, T., Golmard, J., Lascols, O., & Duguet, A. (2014). Will students pass a competitive exam that they failed in their dreams? Consciousness and Cognition, 29, 36-47 DOI: 10.1016/j.concog.2014.06.010

further reading
Does sleeping face-down induce more sexual dreams?
Be careful while you sleep – dreams of jealousy and infidelity spell relationship trouble the next day

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

Psychologists investigate a major, ignored reason for our lack of sleep – bedtime procrastination

Short term, lack of sleep scrambles our mental functioning. Long term, the health consequences can be dire. What’s stopping us from getting enough?

For many, adequate sleep is elusive because of sleep disorders, including varieties of insomnia. For others there are practical challenges – baby care or night shifts, for example. A new study focuses on another major, yet strangely overlooked, reason – bedtime procrastination. You want to go to bed early. You know you need to get to bed. And yet you stay up watching TV, playing video games or working late.

Floor Kroese and her colleagues surveyed over two thousand people (age range 16 to 93) in The Netherlands about their sleep habits and self-control. The participants also kept a seven-day sleep diary. All were free from medical sleep disorders or night shift jobs. Overall, the group averaged 7.2 hours sleep a night, but 17.5 per cent of them felt certain they didn’t get enough sleep in general, and over 50 per cent believed they didn’t get sufficient sleep on two nights or more a week.

Looking at the factors that were associated with insufficient sleep, demographics such as age and gender accounted for 8 per cent of the variation in sleep (being younger and female went hand in hand with less sleep), and external factors outside of one’s control accounted for an additional 4.6 per cent. But the headline result is that 12.7 per cent of variation in sleep was explained by self-confessed bedtime procrastination – choosing to engage in activities even though it was time for bed. Lack of self control in general was also associated with insufficient sleep, but this was at least partly explained by co-occurrence of low self-control and greater bedtime procrastination.

“It can be speculated,” the researchers said, “that people who have low self-regulation skills are more likely to keep watching the late night movie, or play yet another computer game despite knowing they might regret it the next morning when waking up tired.”

Kroese and her team are careful to say this is speculation because their methodology does not prove there is a causal role for low self control and bedtime procrastination. It’s possible – indeed likely –  that lack of sleep adversely affects self control, thus increasing bedtime procrastination. Nonetheless, it makes sense that the causality runs in both directions and that lack of sleep is for many a self-regulation problem.

If so, the researchers point out that this self-regulation perspective puts lack of sleep “on par with other health behaviour problems such as getting too little exercise, or making unhealthy food choices.” This has implications not just for how we understand the problem, they explained, but also for highlighting potential interventions that could be borrowed from these other areas, such as the use of “if-then” plans. These rehearsed plans help overcome unhelpful habits by setting up new automatic routines or rules – such as, “if I’m feeling tired, then I will switch off the TV”.

_________________________________ ResearchBlogging.org

Kroese, F., Evers, C., Adriaanse, M., & de Ridder, D. (2014). Bedtime procrastination: A self-regulation perspective on sleep insufficiency in the general population Journal of Health Psychology DOI: 10.1177/1359105314540014

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

What happens when therapists dream about their clients?

We often dream about what we’ve been doing and who we’ve been with, so it should come as little surprise to discover many psychotherapists dream about their clients. In fact a new study reports that nearly 70 per cent of thirteen participating therapists said that they’d had such dreams.

Psychologist Clara Hill and her colleagues asked the 13 student psychotherapists to keep dream journals for the duration of the time they worked at a community clinic – either one or two years. The number of dreams recorded in the journals ranged from 6 to 150 per year, and the proportion that were about clients ranged from 0 to 0.19 (average 0.06). Also, at the end of a period of therapy with a client they’d dreamed about, the therapists took part in an interview with the researchers about their dream experiences and what they’d gained from them.

The student therapists described their dreams about clients as disturbing and directly related to the therapy, often depicting the struggles involved. “Dreams appeared to function as a means for therapists to process difficulties they were experiencing in the therapy with these clients,” the researchers said.

Although unpleasant, the dreams about clients appeared to be beneficial. Therapists described how the dreams of clients led to useful insights. To paraphrase one example, a female therapist dreamt of being in a circus and her client appearing on the back of an elephant, and remaining in the middle of the ring even as the other riders and their elephants left. The therapist said her client looked liked a mannequin and just sat their not interacting with the audience. The dream led the therapist to think about her client’s depression and the possibility she might have been forcing happiness and optimism on her. It also made the therapist realise that she cared for her client, that her client was willing to try new things, but that she (the therapist) needed to adjust her pacing and tone.

“In this rich qualitative examination of these therapists’ dreams, then, we learn that such dreams, though clearly distressing … nevertheless yielded helpful lessons that therapists then effectively applied to their continued clinical work,” said Hill and her colleagues.

There was little evidence that therapists discussed their dreams of clients with their supervisors. Given the apparent insights derived from client dreams, the researchers suggested that therapy training programmes incorporate more focus on working with dreams in supervision. They also suggested expanding this line of research to see whether therapists using other approaches (e.g. CBT, psychoanalysis) also dream of their clients, and whether they too find it beneficial.

The researchers acknowledged some limitations of their study including the small sample size and the fact that keeping dream journals may have encouraged a greater than usual focus on dreams among the participating therapists. However, the researchers didn’t show any scepticism towards the therapists’ claims that their dreams had been beneficial for therapy. Readers of a more scientific persuasion will no doubt demand more rigorous evidence before believing this is really true.

_________________________________ ResearchBlogging.org

Hill CE, Knox S, Crook-Lyon RE, Hess SA, Miles J, Spangler PT, and Pudasaini S (2014). Dreaming of you: Client and therapist dreams about each other during psychodynamic psychotherapy. Psychotherapy research : journal of the Society for Psychotherapy Research PMID: 24387006

–further reading–
When therapists have the hots for their clients

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

"Placebo sleep" can boost your mental performance

Believing that you’ve had a good night’s sleep can influence your mental performance, regardless of how much sleep you actually had. That’s according to a new paper, by Christina Draganich and Kristi Erdal, who tricked students into thinking there’s a medical technique that can establish objectively how well you slept the previous night.

Fifty students first said how well they’d slept. Next, they were wired up to measures of their brain waves, pulse and heart-rate, and half of them were told the fiction that in fact they’d had just 16.2 per cent REM sleep the previous night (below average sleep quality); the other half were told they’d had an above average night of sleep, with 28.7 per cent REM sleep. Confronted with a difficult mental arithmetic task, the students told they’d had a good night’s sleep then outperformed those who were told they’d had a poor night’s sleep. In contrast, their initial subjective sense of their previous night’s sleep quality was not related to their performance.

It might be tempting to take from this first result the idea that we can boost our mental performance if we convince ourselves we slept well last night. However, bear in mind that the students told they’d had a good night’s sleep scored 34.81 on average on the arithmetic test, whereas the average score on this test for an adult is 36. It’s a shame there wasn’t a baseline control condition to see how students would have performed without receiving any information about their sleep quality. Those students told they had a bad night’s sleep scored 22.13 on the test. If anything then, this first result looks like a “nocebo effect”: belief that last night’s sleep was bad undermined performance, but being told last night’s sleep was good made little difference.

A second study was similar but this time, after receiving fictitious positive or negative feedback on their previous night’s sleep, dozens of students completed a range of tests: the same arithmetic task used earlier, a word association task, a measure of visual-motor processing speed, and a digit-span test of short-term memory. Another improvement from the first study is that the researcher who interacted with the participants did not know which condition they’d been allocated to. There were also two control groups – they answered questions about their sleep the previous night and then performed the tests. So they didn’t receive the false “objective” feedback on their sleep quality.

For those who received it, feedback on sleep quality was correlated with performance on the arithmetic task and the word association task, with those told they’d slept well scoring higher than those told they’d had a disturbed night. The students’ initial sense of how well they’d slept, before they received the objective sleep measure, was not correlated with their performance on any of the tests. This was also true for the students in the two control conditions.

This time there was some evidence of a beneficial placebo effect. Students told they’d had a good night’s sleep scored an average of 51 on the word association task, whereas the adult average score on this test is 43.51. It’s shame the researchers didn’t provide the word association scores for the students in the control conditions for comparison. Their scores could have acted as a baseline rather than referring to published adult norms for the tests.

“We have shown that decrements in performance can be elicited when verbal instruction and technological displays convey poor sleep quality to the individual,” the researchers said. “We have also shown that increments in performance can be elicited when verbal instruction and technological displays convey high-quality sleep.”

These results build on a study published ten year’s ago that found people with insomnia experienced less sleep-related anxiety when a real objective measure of sleep (an actigraph) showed that they tended to overestimate how long it took them to get to sleep.

_________________________________

Draganich C, and Erdal K (2014). Placebo Sleep Affects Cognitive Functioning. Journal of experimental psychology. Learning, memory, and cognition PMID: 24417326

–further reading–
Is the benefit of exercise a placebo effect?

Christian Jarrett (@Psych_Writer) is Editor of BPS Research Digest

Be careful while you sleep – dreams of jealousy and infidelity spell relationship trouble the next day

Have you ever dreamt of arguing with your partner, or dreamt they were unfaithful, and then – irrational as it may be – found yourself in a bad mood with them the next day? This will be a familiar scenario to many, and yet such apparent effects of dream content on our real-life relationships have only now been studied for the first time.

Dylan Selterman and his colleagues asked 61 undergrads (aged 17-42; 47 women) to keep detailed, morning dream diaries for two weeks. Each evening the participants also kept records of what they’d been up to in the day, including their relations with their partner. Having a partner of at least six months duration was a requirement for taking part in the research.

Overall, last night’s dream content was associated with the ensuing day’s behaviour in ways you’d expect. Dreaming last night of being jealous of one’s partner, or dreaming of arguing, went hand in hand with more rows during the ensuing day. Dreaming of infidelity by oneself or by one’s partner was associated with lower feelings of intimacy. These patterns held even after controlling for the previous day’s activity, and factors such as gender and relationship length.

Some dream-behaviour associations were moderated by other factors the researchers looked at including anxious attachment and the seriousness of the relationships. For instance, dreaming of sex with your partner was associated with feeling more intimate during the following day, but only for those in more committed “interdependent” relationships. For those low in interdependence, dreaming of sex with one’s partner actually tended to be followed by lower feelings of love and intimacy the next day, possibly because the sex in the dreams wasn’t welcome or enjoyable.

Similarly, jealous dreams tended to be followed by reduced feelings of love and intimacy the next day, but not for those with an avoidant attachment style. This is possibly because such people have high baseline levels of jealousy anyway.

Selterman and his colleagues admitted they haven’t demonstrated conclusively that dream content is causing changes to behaviour the next day. Despite the study’s longitudinal design, there remains the possibility that the observed patterns were due to daily activity affecting dreams. However, this seems unlikely because the researchers controlled for previous day’s activity, and most of the dream content / next-day behaviour links they uncovered failed to correlate when looked at in reverse – i.e. when they looked to see if daily behaviour recorded in the evening was associated with dream recall the next morning.

If dream content really does affect our relationships in the ways implied by this research, Selterman and his team think the mechanism is probably similar to the way we’re primed by our thoughts and surroundings during waking life. “When recalling a dream after waking, the content and/or emotions are active in the mind, and once they are active, may influence subsequent behaviour,” they said.

It seems amazing that no-one has investigated this possibility before, but the researchers emphasised that this is the first ever systematic study of the potential for dreams to affect daily activity. It adds to plentiful previous research showing how daily activities affect dream content. “The findings support the idea that dreams are an important component of human social life, the scientific examination of which may provide unique insight into close relationship processes,” they said.

_________________________________ ResearchBlogging.org

Dylan F. Selterman, Adela I. Apetroaia, Suzanne Riela, & Arthur Aron (2014). Dreaming of You: Behavior and Emotion in Dreams of Significant Others Predict Subsequent Relational Behavior. Social Psychological and Personality Science DOI: 10.1177/1948550613486678

–further reading–
does sleeping face-down induce more sexual dreams?

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

Owls get poorer school grades than larks

From our enlightened 21st century perches, we frown upon the old practice of forcing left-handers to use their right hands. And yet, today our entire society still functions in a way that is biased against those “owls” whose chronotype means they function better in the evenings. Nowhere is this more evident than in schools, which typically start early in the morning, even though the tendency towards owl-hood is known to peak in adolescence. Now a new investigation of teenagers in Germany has confirmed that owls at school tend to perform worse in their studies than larks, even after factoring out other possible explanations.

Franzis Preckel and her colleagues assessed 272 students (average age 16; 127 girls) from five German schools about their chronotype, educational attainment and a raft of other motivational and psychological measures. Students who were owls, with a preference for the evenings, tended to report having poorer school grades across maths, science and languages. This has been shown in previous studies. The novelty of this research is the comprehensive number of other factors that were investigated. Ultimately, Preckel’s team showed that a student with a greater preference for the evening will tend to score poorer grades at school than a more morning-oriented student (a Lark), even if both students are matched for sex, cognitive ability, motivation, conscientiousness and a trait known as “need for cognition” (a preference for thinking hard). The unique variability in academic performance explained by owl-hood was between two and four per cent.

Why should an evening-orientation lead to poorer grades? The researchers assessed day-time sleepiness – the obvious explanation – but this did not correlate with school grades. Another clue is that owls tend to consume more drugs and are less motivated and conscientious. And yet the link between evening-orientation and poor grades still held even after controlling for motivation and conscientiousness. The last, most plausible explanation, therefore, is that owls perform worse at school because of synchrony effects – that is, people tend to excel when tested at what is the optimal time of day for them. Early starts at school mean students who are owls spend more time studying at, what for them, is a sub-optimal time of day.

Preckel and her colleagues said their findings have obvious educational implications. “In general, parents, teachers, and students themselves should learn more about chronopsychology and its effects on everyday life and learning,” they said.

Thankfully there are signs that the educational establishment is waking up to the importance of chronopsychology, at least in the UK. Monkseaton High School in Tyneside first trialled late starts (10am) in 2009 and initial results in 2010 suggested that grades had subsequently risen and absenteeism fallen. There are also reports that the recently opened UCL Academy in London has instituted 10am start times (although the Daily Mail reported incorrectly that it is the first UK school to do so).

_________________________________ ResearchBlogging.org

Preckel, F., Lipnevich, A., Boehme, K., Brandner, L., Georgi, K., Könen, T., Mursin, K., and Roberts, R. (2013). Morningness-eveningness and educational outcomes: the lark has an advantage over the owl at high school. British Journal of Educational Psychology, 83 (1), 114-134 DOI: 10.1111/j.2044-8279.2011.02059.x

–Further reading–
Why teens should have their music and sports lessons in the evening
Students: it’s time to ditch the pre-exam all-nighter

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

Does sleeping face-down induce more sexual dreams?

It’s a common experience for us to incorporate sounds we hear while we’re sleeping into the narrative of our dreams. The real car alarm outside becomes a police siren in our exciting chase through dreamland. Given the way activities and sensations from the real world permeate our dreams, the author of a new study, Calvin Kai-Ching Yu at Hong Kong Shue Yan University, has investigated whether the simple fact of our sleeping position can also affect the kinds of dreams we’re likely to have.

Yu surveyed 670 people (average age 19) – including 227 men and 443 women – about the content of their dreams, their dream intensity, their usual sleeping position (face up, face down, or lying on their side), and their personality.

Yu’s main finding is that sleeping more often in a prone (face down) position is associated with a higher prevalence of experiencing particular dream themes, including: being locked up; dreaming about hand tools; sexual experiences; being smothered and unable to breath; swimming; and being nude. Although sleeping more often in a prone position was related to personality factors (negatively associated with conscientiousness and correlated with neuroticism), this didn’t fully explain the link between sleep position and dream content. Of the 476 participants who reported having a dominant sleep position, only 5 per cent were habitual prone sleepers.

Yu thinks a prone sleeping position triggers particular kinds of dream content because of the way that the pressure on the body, including the genitals, and difficulty breathing, is converted into dream experiences. Sometimes this is done in a symbolic way, he argues, (hence the dreams about hand tools). Yu endorses a Freudian view of dreams, suggesting they protect sleep “by quenching the internal needs or eliminating the cues that alert the sleeping ego to the existence of the outer world.”

In contrast to the associations between prone sleeping position and dream content, the frequency of sleeping in a supine (face up) or lateral position was almost entirely unrelated to the prevalence of different dream themes.

A major criticism of this research is the fact that participants were relied on to accurately recall their sleeping position and their dream content, a shortcoming that Yu acknowledged. The lack of any comparison between genders also seemed an unfortunate omission.

“This study provides the evidence that dream experiences, and in particular dream content, can be influenced by body posture during sleep,” Yu concluded. His findings add to past research showing that right-sided sleepers had more positive dreams and fewer nightmares than left-sided sleepers.

_________________________________ ResearchBlogging.org

C K-C Yu (2012). The effect of sleep position on dream experiences. Dreaming DOI: 10.1037/a0029255

–Further reading– Paraplegics walk in their dreams.

Post written by Christian Jarrett for the BPS Research Digest.