Daily Archives: December 23, 2024

The 8 science-backed secrets to a more restful night’s sleep

The author of The Great Gatsby, F Scott Fitzgerald, once said, “The worst thing in the world is to try to sleep and not to.” He was far from alone in that sentiment. Listen to any group of bleary-eyed new parents and one of them is likely to compare sleep deprivation to a form of torture. Lack of sleep feels horrible. It doesn’t just leave you feeling down, dozy, and demotivated, it makes you eat more. As much as 385 calories, say researchers at King’s College London, due to a drop in our levels of the satiety hormone leptin and a rise in the ‘hunger hormone’ ghrelin.
It also causes changes to our gut bacteria, makes us more sensitive to pain and can lead to trouble in deciphering other people’s emotions. 
After a single night of poor sleep, it’s possible to see changes in our blood. A study by Western Norway University of Applied Sciences showed that 34 proteins were significantly affected after six fewer hours of shut-eye, including ones related to immune suppression and impaired blood-clotting. 
When it comes to trying to improve our sleep, most of us will have heard the same pieces of advice time and time again. There’s limiting your caffeine past midday (stop drinking it 8.8 hours before bedtime, to be precise) and not exercising hard within an hour of sleeping (light exercise is fine). 
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Others are to use the bedroom only for bed-related activities – sleep and sex – and leave your devices somewhere else. And then there’s making sure you go to sleep at the same time every day, which comes with the added benefit that a regular routine can extend your lifespan.
Obviously, if you’re really struggling to sleep, you should see a doctor. “You might have an underlying issue that requires being properly addressed,” says Dr Guy Leschziner, a professor of neurology and sleep medicine at Guy’s and St Thomas’ NHS Foundation Trust, London.
“It’s easy to attribute poor sleep to insomnia, but there may be other conditions that explain your symptoms, for example sleep apnoea.”
But in the quest for the perfect night’s slumber, here are some fresh ideas…
1. Keep to an eating schedule
Eating at specific times can help improve the quality of your sleeping schedule – Photo credit: Getty Images
While increasing your intake of fruit and vegetables can improve sleep, according to a University of Michigan study (as can a Mediterranean or anti-inflammatory diet), it’s not just what you eat that matters, but when. 
Researchers in the field of chrononutrition (how the timing of food intake relates to your body clock) have found that eating at specific times, as well as certain food/time combinations, can affect sleeping patterns.
If the main issue is struggling to nod off in the first place, you could try a high-glycaemic index (GI) meal four hours before bedtime. Research suggests that those who ate jasmine rice, which has a GI of 109, took an average of nine minutes to fall asleep, while those who ate a low GI meal took 17.5 minutes.
High-GI meals result in a greater concentration of the amino acid tryptophan in the bloodstream.
This is converted into serotonin and ultimately melatonin, which regulates the sleep-wake cycle. Timing is important, though – the same high-GI meal just one hour before bedtime doesn’t have the same effect, with people taking nearly 15 minutes to drift off.
Late eating has been found to be a no-no in other studies, too. Researchers from the University of Michigan found that people who ate within an hour of bedtime were more likely to wake during the night; they slept longer, but this was due to a need to compensate for having less-efficient, interrupted sleep. 
Another study by the Universidade Federal de São Paulo, Brazil, found that adult men who ate more fat late at night had lower sleep efficiency. Disruptions to women’s sleep, meanwhile, were linked to both fat consumption and overall calories.
Eating at the wrong times may impact the ‘clocks’ in your cells too.
“We have a central clock in a region of the brain called the suprachiasmatic nucleus, but also clocks in every major tissue and probably most/all cells in the body,” says Jonathan Johnston, professor of chronobiology and integrative physiology at the University of Surrey.
“There’s strong evidence from animal studies and the few available human studies that meal timing is a dominant synchroniser of some circadian clocks outside of the brain.”
2. Squeeze your muscles
PMR can help reduce stress and anxiety preventing you from getting to sleep faster – Photo credit: Getty Images
When you’re looking to nod off, try squeezing and relaxing your big muscle groups. It’s a technique known as progressive muscle relaxation (PMR) and can help with insomnia, according to studies, and improve your naps. 
Dr Katharine Simon of the University of California, Irvine, compared people who did PMR before a nap to those who went to sleep listening to relaxing music. The results showed that the former group had 125 per cent more deep sleep and an improved sleep pattern.
“PMR before napping can enhance the amount of restorative sleep one obtains, and better sleep is linked to improved attention, creativity and cognitive function,” she says.
There are lots of instructional PMR videos online. Its effect on deep sleep – which is critical for supporting new memories, immune functioning, and physiological restoration – is likely to be seen for nighttime sleep, too, although more research is needed.
As for how long to nap for, it depends on your desired outcome, says Simon. “For a quick refresh and better attention, shorter naps suffice. For retaining new learning, a 60-minute nap that includes deeper, restorative sleep stages is beneficial.
To enhance creativity, aim for a 90-minute nap to cycle through all sleep stages, including rapid eye movement (REM) sleep.”
The timing of a nap can influence the type of sleep, with early morning kips often having more REM sleep compared to ones in the late afternoon.
3. Ignore your sleep tracker…maybe
Smart watches can be inaccurate when it comes to tracking sleep, causing additional stress – Photo credit: Getty Images
They come in various forms: smartwatches, wrist-worn fitness trackers, and, more recently, smart rings. They’re meant to help improve your sleep, but are they making things worse?
For a person who suffers from insomnia caused by excessive worrying, sleep tracking can be counterproductive, says Dr Mathias Baumert, who studies sleep technology at the University of Adelaide, Australia. “It may create additional stress on someone ‘needing to fall asleep’.”
A University of Oxford study may offer further evidence that ignorance (in the case of our sleep patterns) may well be bliss. Some participants were given smartwatches that had been manipulated to show a false report of a poor night’s sleep, and had a lower mood, difficulties with thinking processes and increased sleepiness.
Those who were shown a report of a good night exhibited the opposite. A separate study by the University of Warwick, obtained similar results.
“Even though a sleep-tracking device might say you slept poorly last night, your own perception of your sleep quality may be quite positive,” says Dr Anita Lenneis, lead author of the study. 
The devices aren’t always accurate either. “They aim to gauge sleep indirectly, based on sensors that capture body movement (actigraphy) and physiological variables that tend to be different during sleep than while awake, most commonly pulse rate, respiration and temperature,” says Dr Baumert.
“Unless you measure brain activity directly, via electroencephalography, you never know for sure if a person is asleep.”
4. Put in some worry time
Writing down some worries instead of keeping them all in your head can help ease some stress when it comes to sleeping – Photo credit: Alamy
By scheduling a specific time of the day when you can focus on the things that are worrying you, and jot them down on a piece of paper, you may lessen those sleep-destroying thoughts that can rear their head at bedtime. 
“It’s better to write the worries down rather than thinking about them,” says Dr Chris James, a consultant clinical psychologist who runs an online practice specialising in sleep.
“Thinking can lead to rumination, where you keep turning the thoughts over and over in a loop, which can be exhausting and make you feel more worried as the worries snowball.”
The act of writing down your worries creates “mental distance” from them, says James, so your brain can “use its ability to apply logic and greater perspective.” Knowing that you’ve ‘done’ your worrying earlier in the day, and that you have more time to do it again the following day, means that if nagging thoughts do pop up as you go to sleep, you can tell yourself ‘I don’t need to think about this right now.’
Schedule your worry time for whenever is most convenient, although don’t put it too close to bedtime in case it starts to “wake your brain up”, says James.
For anyone who might find it awkward, he adds: “A good thing about the strategy is that it’s something you can do privately, so you could write down your worries in a note on your phone and it would just look like you’re messaging.” 
5. Sort out your bedtime thoughts
Poor planning & problem-solving skills can lead to more worrisome thoughts and, thus insomnia. – Photo credit: Getty Images
If your scheduled worry time isn’t stopping those bothersome thoughts from intruding on your bedtime, another option is to try cognitive refocusing treatment for insomnia (CRT-I). First used with military veterans, its aim is to help people drift off by changing the style and content of their pre-sleep thoughts. 
In poor sleepers, pre-sleep ponderings tend to relate to planning and problem-solving and are likely to be more unpleasant than those of good sleepers, according to a review by Université Laval in Québec, Canada. Changing those physiologically and emotionally arousing thoughts to non-stimulating ones is the key.
In a study by Syracuse University, New York, a group of insomniacs were told to put in place the usual sleep hygiene rules – such as no caffeine after midday, keeping the bedroom dark and no exercise within two hours of bedtime – but half the group worked with an instructor to identify three topics each that would be compelling enough to maintain their attention and replace existing thoughts.
These could include new meal recipes or plots from their favourite movies and TV shows.
The important thing was that the chosen topics had to be “devoid of emotion-laden, negative, exciting or worrisome content,” say the researchers. Participants were asked to focus their attention on these topics when getting to sleep (and if they woke in the night) and do nothing else. Even looking at the clock could disrupt focus.
“The presumed mechanism is that CRT-I reduces emotionally and physiologically activating thought content (for example, worry, rumination, dwelling on daily and future concerns, and thinking about the consequences of poor sleep) to improve the calm and relaxed state that may promote sleep onset,” says Prof Les Gellis, who led the study.
“We found that at the [one-month] follow up, participants in the group showed a large reduction in nighttime arousal while the sleep hygiene group showed only a small reduction.” 
6. Spend less time in bed
Spending as little time in bed as possible, beyond what’s needed to sleep, will improve the quality of your sleep overall – Photo credit: Getty Images
In sleep restriction therapy (SRT), the aim is to reduce the amount of time a poor sleeper spends in bed beyond the average number of hours they’re actually asleep. Simply increasing your amount of bed time in the hopes that it will increase your sleep doesn’t work, according to Stephanie Romiszewski, a sleep psychologist and co-founder of re:sleep. 
“Rather, it tends to make things worse. Sleep becomes more broken, more diluted and sleep anxiety can increase, further exacerbating the lack of sleep,” she says. “By reducing time in bed to the actual average sleep time, you improve sleep efficiency – getting to sleep becomes easier and the quality improves.”
It’s then possible for people to increase their bed time incrementally to add further sleep duration if needed. Although, as Romiszewski stresses, some people “just need to increase sleep quality and not duration”.
The gentler cousin of SRT is sleep compression: making small reductions in the time spent in bed rather than a dramatic cut all at once. “Sleep anxiety is more easily managed as you’re getting used to less time in bed gradually, which seems counterintuitive to start with, and also the process relies on building a strong sleep drive at predictable times of the day,” says Romiszewski.
The results of sleep compression can be “very powerful”, if the person keeps to a rigid plan over time. 
It needs to be stressed that not everyone is a suitable candidate to undertake SRT or sleep compression. People with bipolar disorder, seizures or those with untreated daytime sleepiness or mental health conditions should work with experienced sleep experts. 
7. You can leave your socks on
Additional warmth from wearing socks in bed can trigger your body to fall asleep earlier – Photo credit: Getty Images
There have been multiple studies to suggest that one method to improve sleep is to go to bed with your socks on. Researchers at Seoul National University, South Korea, found that people were able to nod off 7.5 minutes earlier, slept for a full 32 minutes longer, and woke up less often during the night. 
Leaving your socks on taps into our body’s preference for a slightly lower core temperature at night, which is driven by a redistribution of blood to the skin, most prominently at our extremities, under the guidance of our biological clock.
When our hands and feet are warm, it’s a sign that we’re ready for sleep, via activation of the hypothalamus in the brain, which is full of temperature-sensitive neurons and is strongly involved in sleep regulation.
“Warm feet go hand-in-hand with sleep, in a casual way,” says Dr Roy Raymann, a leading sleep neuroscientist and founder of the Sleep Czar consultancy. “If our feet are too cold, it prevents the brain area switching to a sleep-permissive state.”
There’s an added, perhaps surprising, advantage, too: wearing socks in bed might just give your love life a boost. Researchers at the University of Groningen, the Netherlands, studying male and female orgasms found that only 50 per cent were able to climax.
But when the participants wore socks, the figure jumped to 80 per cent. Who knew wearing socks in bed could set the mood, as well as give you a good night’s sleep?
8. Catch some early rays
Getting 30-45 minutes of daytime sunlight a day will help make you more alert & improve your mood. – Photo credit: Getty Images
“Morning sunlight, particularly bright sunlight, can have important consequences on your circadian rhythm,” says Leschziner.
“So, if you’re one of these people with a delayed sleep phase – which means you’re potentially a significant night owl, wishing to go to bed late and wake up very, very late – then morning sunlight pushes your circadian rhythm forward. It makes you more able to go to bed a little earlier and wake up a little earlier.” 
Early sunlight has this effect because there are cells in our retinas, not related to vision, that relay information about light exposure directly to a deep part of our brains, the suprachiasmatic nucleus, which encodes the master circadian clock – the keeper of our circadian rhythm.
“Daytime sunlight may help improve mood and make you feel more alert as well,” adds Leschziner.
The recommended amount of sunlight is 30–45 minutes, shortly after waking up. On overcast days, a suitable alternative would be a lightbox with an intensity approximating natural sunlight, or 10,000 lux.
In a study carried out by researchers at the University of Queensland, Australia, young adults were exposed to morning sunlight and found that their circadian rhythms shifted as much as two hours forward.
About our experts
Dr Guy Leschziner, qualified from Oxford and Imperial College before going to Guy’s and St Thomas’ NHS Foundation Trust.
After earning his PhD in the genetics of epilepsy at Imperial College London and the Wellcome Trust Sanger Institute, Cambridge, he then completed his higher training in neurology at Charing Cross Hospital, the National Hospital for Neurology and Neurosurgery, Queen Square, and once again at Guy’s and St Thomas’.
Jonathan Johnston is a professor of chronobiology and integrative physiology at the University of Surrey.
After earning his PhD at the University of Manchester, he went on to become a postdoctoral research fellow at the University of Aberdeen, a senior lecturer in neuroscience, and then a reader in chronobiology and integrative physiology at the University of Surrey.
Dr Katharine Simon is an Assistant Professor of Pediatrics at the University of California, Irvine. Her key research interests are development, learning and memory, memory consolidation, sleep, and pediatric populations.
Dr Mathias Baumert, is an Associate Professor at the University of Adelaide, Australia. An expert in biomedical signal processing, he has become well-known for his focus on dynamic electrocardiography and sleep research.
Dr Anita Lenneis is a Doctor of Philosophy working at the University of Warwick’s Department of Psychology. Conducting research in Personality and Health Psychology, she is currently working on a project focused on ‘Chronotype and its relation to self-and observer reported personality traits and facets.’
Prof Les Gellis is an Associate Teaching Professor at Syracuse University. With interests including the understanding of sleep behaviours and cognitive interventions to prevent insomnia, his research focuses on both the causes and treatment of insomnia, along with related sleep deficiancies.
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Scientists find 49 genetic regions linking ADHD and dyslexia

A new study published in Molecular Psychiatry has uncovered genetic connections between dyslexia and attention deficit hyperactivity disorder (ADHD), offering the strongest evidence yet of shared genetic influences between the two conditions. Scientists analyzed vast datasets encompassing millions of participants, providing a clearer picture of how genetic factors may contribute to the frequent co-occurrence of these neurodevelopmental traits. The findings not only confirm the genetic overlap between dyslexia and ADHD but also identify novel genetic variants associated with both conditions.Dyslexia is a learning difficulty characterized by persistent challenges with reading, spelling, and writing despite normal intelligence and adequate education. It affects how the brain processes language, often leading to difficulties in recognizing written words, decoding sounds, and spelling accurately.ADHD is a neurodevelopmental condition marked by persistent patterns of inattention, hyperactivity, and impulsivity that interfere with daily functioning. Individuals with ADHD may struggle with maintaining focus, organizing tasks, or controlling impulses, which can impact academic, occupational, and social activities.Dyslexia and ADHD often co-occur, with approximately 25-40% of individuals diagnosed with one condition also meeting the criteria for the other. While previous research has pointed to genetic influences in both disorders, the exact nature of their genetic relationship remained unclear. Most genetic studies on neurodevelopmental and psychiatric disorders have focused on individual conditions, neglecting the broader connections among traits.“At the outset of this study, we had solid evidence suggesting a genetic link between dyslexia and ADHD. However, it was far less clear whether dyslexia might also share genetic links with other childhood traits, particularly autism,” explained study author Austėja Čiulkinytė, a PhD student in the Translational Neuroscience PhD program at the University of Edinburgh.“Previous genetic studies have focused on comparisons of two traits, such as studying dyslexia and ADHD or dyslexia and autism. We wanted to take a broader approach by using a technique that examines the underlying genetics of multiple traits together. This allowed us to investigate whether there might be a shared set of genes across all neurodevelopmental traits, or whether they form genetically distinct categories.”To investigate the genetic overlap between dyslexia and ADHD, the researchers utilized publicly available genetic data from large-scale studies. The datasets included information on over 453,000 individuals diagnosed with one of ten neurodevelopmental or psychiatric conditions, such as autism, anxiety, and schizophrenia. Dyslexia-related genetic data came from an analysis of over one million participants, conducted in collaboration with the genomics company 23andMe.The research team used advanced statistical methods to build a genetic model that clustered these conditions based on shared genetic influences. They employed genomic structural equation modeling, a technique that identifies patterns of genetic correlations among multiple traits. The analysis focused on identifying latent genetic factors—underlying clusters of traits with shared genetic liability—and pinpointing specific genetic variants that influence both dyslexia and ADHD.“By studying many related behaviors together, we are able to boost the statistical power for gene discovery,” said senior author Michelle Luciano, a professor of psychology and language sciences at the University of Edinburgh.The researchers identified a new genetic factor that clusters dyslexia and ADHD together, which they referred to as the “attention and learning difficulties” factor. This latent factor represents the genetic commonalities that underlie traits related to challenges in reading, attention, and cognitive performance. This factor was separate from other clusters of traits, such as neurodevelopmental disorders, internalizing disorders (e.g., anxiety and depression), and psychotic disorders (e.g., schizophrenia and bipolar disorder).Dyslexia and ADHD displayed a moderate genetic correlation of 0.40, indicating a substantial overlap in genetic influences. This finding is consistent with previous twin and family studies, which have shown that these two conditions often co-occur and may share common biological pathways.Interestingly, the study found no significant genetic correlation between dyslexia and autism, despite some overlapping traits, such as difficulties with sensory processing. This suggests that dyslexia and ADHD are more closely related genetically than dyslexia and autism.“Our original hypothesis was the opposite of what we found,” Čiulkinytė told PsyPost. “Initially, we thought that dyslexia, ADHD, and autism would all fall under the same genetically correlated cluster. However, the data showed that this was not the case.”“In this study, we show that dyslexia and ADHD in fact share a distinct set of genetic influences, which are different from those of other neurodevelopmental traits. We propose that in the context of genetics, ADHD might be better understood as an attention and learning difficulty (like dyslexia) rather than a purely neurodevelopmental trait (like autism).”One of the most groundbreaking aspects of the study was the discovery of 49 genomic regions associated with both dyslexia and ADHD, 43 of which had not been previously identified. These regions were mapped to 174 protein-coding genes, many of which play crucial roles in brain development, synaptic signaling, and cognitive processes.Among these genes, SORCS3, TRAIP, AMT, and TCTA emerged as particularly noteworthy candidates. For example:SORCS3 is involved in neural signaling and synaptic plasticity, processes critical for learning and memory. It has been linked to reduced spatial learning abilities, which are often affected in both dyslexia and ADHD.TRAIP is essential for maintaining genome integrity and has been associated with cognitive function and intelligence in previous studies.AMT plays a role in neuronal development and has been strongly associated with educational attainment, a trait negatively impacted by both dyslexia and ADHD.TCTA has been implicated in cognitive performance and problem-solving abilities, further highlighting its relevance to attention and learning processes.The attention and learning difficulties factor identified in the study showed strong correlations with traits related to academic and cognitive performance. For example, individuals with genetic predispositions to dyslexia and ADHD were more likely to struggle with linguistic and mathematical tasks, such as reading comprehension and problem-solving. The factor also negatively correlated with measures of educational attainment, such as the likelihood of obtaining higher qualifications or completing formal education.The study sheds light on the complex genetic connections between dyslexia and ADHD, offering a new framework for understanding their frequent co-occurrence. However, there are some limitations. The genetic datasets included primarily individuals of European ancestry, which may limit the generalizability of the findings to other populations. Future studies should incorporate more diverse genetic data to ensure broader applicability.The study also did not include conditions such as dyscalculia or developmental language disorders, which often co-occur with dyslexia and ADHD. Including these traits in future research could provide a more comprehensive understanding of the genetic architecture of learning difficulties.“In the future, it would be great to extend this analysis by including datasets on genetic influences of other learning difficulties, particularly dyscalculia and dyspraxia,” Čiulkinytė said. “This will help us to better define the set of genes affecting attention and learning difficulties in the broad sense.”“I think it is important to highlight that our study focuses on population genetics of complex traits: we are studying millions of small genetic changes, each with a tiny effect, across thousands of individuals,” she added. “This type of study allows us to better understand the overall pattern of how dyslexia and ADHD manifest, uncover potential genetic causes, and suggest that they both might benefit from similar management approaches. However, it does not mean that every individual with ADHD is also dyslexic or vice versa.”The study, “Genetic neurodevelopmental clustering and dyslexia,” was authored by Austeja Ciulkinyte, Hayley S. Mountford, Pierre Fontanillas, 23andMe Research Team, Timothy C. Bates, Nicholas G. Martin, Simon E. Fisher, and Michelle Luciano.