Latest news with #circadianrhythm
New York Times
6 hours ago
- Health
- New York Times
The Battle to Beat Jet Lag: Can an App Make a Difference?
Nothing undermines the joy of travel quite like a bad case of jet leg. That's why an entire industry has popped up to help deal with it, hawking solutions like light therapy glasses, targeted supplements, apps and coaching. But do any of them actually work? I put two popular methods to the test on a two-week journey to Asia in May. I flew from New York City, where I live, to Seoul and Taipei, Taiwan — both on the other side of the globe, a difference that is literally night and day — and then back home. The two apps to which I ceded control of my daily rhythms, Flykitt and Timeshifter, are personalized programs based on scientific approaches to jet lag. Both directed me when to sleep, get light exposure, drink caffeine and take supplements. But they took different approaches: Flykitt featured a heavy vitamin regimen, while Timeshifter focused on preparing for jet lag days before flying. The science of jet lag Both apps rely on circadian science, the study of the body's internal clocks. The central clock is in the brain and follows a roughly 24-hour cycle. Many mental, physical and behavioral changes in the body, such as hormone release, and sleeping and waking, are influenced by the circadian clock. Research shows that exposure to light plays a key role in synchronizing these rhythms to the outside world. Jet lag happens when the body clock falls out of sync with the local time, resulting in discomforts like poor digestion, foggier memory and focus, and interrupted sleep. Want all of The Times? Subscribe.
Yahoo
21-07-2025
- Health
- Yahoo
Expert shares the surprising role cortisol plays in our sleep — and why it's just as important as melatonin
When you buy through links on our articles, Future and its syndication partners may earn a commission. You've likely heard of cortisol as 'the stress hormone,' the one that spikes when your boss drops a big project in your inbox or when you're running late and stuck in traffic. But cortisol is more than just your internal 'let's get out of here' system; it's also a key player in how your body regulates sleep. This sleep hormone follows a natural 24-hour rhythm that helps you wake up feeling alert and allows the body to properly wind down at night. When it's not functioning properly, your sleep may suffer. We connected with Andrew Franklyn-Miller, MBBS, PhD, Chief Medical and Innovation Officer at Nuritas, and reviewed research on the relationship between sleep and cortisol, to share how cortisol plays a role in our explore the science behind how cortisol interacts with melatonin and your body's circadian rhythm, how it aids rest or hinders it and expert-backed ways to keep cortisol in check throughout the day so you can reap more, better sleep. What is cortisol? Cortisol is a glucocorticoid hormone produced by the adrenal glands. It's related to quite a few responses in the body, from handling the body's stress response, to regulating inflammation, immune function and impacting metabolism. It's also integral to regulating the body's sleep-wake cycle, interacting with hormones like melatonin and aligning with the circadian rhythm—the natural times your body wakes up and falls asleep. 'Cortisol promotes alertness by mobilizing energy stores, increasing blood glucose, and enhancing cognitive function during waking hours,' says Dr. Franklyn-Miller. Why is cortisol important for sleep? Cortisol is essential for a healthy sleep-wake cycle because its peaks and dips impact how quickly you fall asleep, when you wake up the next morning and may even impact your sleep cycles as you snooze. When cortisol is disrupted, for example, if it's surging in the evenings due to psychological stress, it can impact sleep quality, making it more challenging to fall asleep and stay asleep through the critical sleep stages, according to this study. Cortisol helps you wake up in the morning Think of cortisol as part of your body's natural 'get up and go' response. According to research, the cortisol awakening response (CAR), a physiological response that results in a sharp rise in cortisol levels within 30 to 45 minutes of waking, prepares the body for daily activities by boosting metabolism and vigilance. Cortisol levels peak in the early morning and decline throughout the day, reaching their lowest point at night to facilitate sleep onset and maintenance. 'While cortisol amplifies metabolic readiness, neural networks and neurotransmitters like the neurotransmitter orexin are primary in initiating and sustaining wakefulness,' says Dr. morning cortisol levels can contribute to difficulty waking and feelings of lethargy, making it feel particularly tough to get out of bed in the morning. Cortisol helps you wind down in the evening Cortisol and melatonin are the seesaw hormones that help with sleep. Cortisol is suppressed at night when melatonin is high, allowing for restful sleep. As morning approaches, rising cortisol levels inhibit melatonin production, making wakefulness easier, so you feel less groggy in the morning. 'Dysregulation, such as stress-induced cortisol elevation at night, can suppress melatonin synthesis, delaying sleep onset or reducing sleep depth,' says Dr. Franklyn-Miller. Cortisol can impact your sleep cycles Tiny pulses of nocturnal cortisol still spike during the night, especially between sleep stages, particularly during rapid eye movement (REM) sleep or brief awakenings, says Dr. Franklyn-Miller. In healthy sleepers, these blips act as micro-check-ins, making sure your body temperature, blood sugar, and memory-storage tasks stay on track. 'However, excessive spikes, often triggered by stress, anxiety, or sleep disorders like insomnia, can disrupt sleep architecture by reducing deep slow-wave sleep or fragmenting REM sleep,' he says. Those middle-of-the-night disruptions negatively impact sleep quality, causing fatigue and impairing function during the day. Not getting enough sleep has been related to higher levels of cortisol. Can cortisol disrupt sleep? Yes, cortisol changes can disrupt sleep. If it's not higher in the morning and lower in the evening, it can impact your ability to fall asleep and stay asleep. Low morning levels of this stress hormone, cortisol, can contribute to difficulty waking and feelings of lethargy. The CAR is critical for mobilizing energy and promoting alertness, and its blunting, as seen in adrenal insufficiency or chronic fatigue syndrome, can lead to sluggishness and trouble getting out of bed, Dr. Franklyn-Miller says. Other factors, such as poor sleep quality or circadian misalignment, may exacerbate this. If you're under chronic stress, the body's fight-or-flight response (hi, cortisol) doesn't power down as it should. That can have a direct impact on your ability to fall asleep, stay asleep, and wake up feeling rested. How to regulate cortisol levels for better sleep As of right now, many popular wearables can't detect cortisol levels in sweat to tell you if that hormone is operating optimally or not. But you can try to help regulate cortisol by supporting healthy circadian rhythm functioning, Dr. Franklyn-Miller suggests. Try these tips:Get light exposure after waking in the morning. Aim for 10 to 30 minutes of natural sunlight or bright light (10,000 lux) within an hour of waking to boost the CAR and suppress melatonin so you feel more awake and alert. Stick with a consistent sleep schedule. There's a reason you read this tip in most of our sleep articles: Because it works. Regular bed and wake times stabilize circadian rhythms, ensuring low nighttime cortisol and a robust morning peak. Practice stress management. Aim for at least 10 minutes daily to reduce chronic stress and lower nighttime cortisol, suggests research in the Journal of Clinical Endocrinology & Metabolism (2005). Better stress management can result in falling asleep faster and staying asleep. Eat a balanced diet. Try to keep meals lower in carbohydrates closer to bedtime to stabilize blood sugar and help prevent cortisol spikes from hypoglycemia, suggests Dr. Franklyn-Miller. Avoiding late-in-the-day caffeine or heavy meals can help with evening cortisol remaining low. Be mindful of exercise timing. Try to give your body a few hours to unwind after an evening exercise sesh if that's the only time you can squeeze it in. Moderate exercise in the morning or afternoon supports healthy cortisol rhythms, while intense evening workouts may elevate nighttime cortisol, according to the Journal of Neuroendocrinology (2003). Limit blue light at night. Reducing screen time can help enhance melatonin and suppress cortisol. Use relaxation techniques before bed. Performing calming activities like reading or gentle yoga can lower evening cortisol, focusing on increasing heart rate variability and parasympathetic nervous activity, promoting restful sleep, according to the Journal of Clinical Endocrinology & Metabolism (2005).
News.com.au
21-07-2025
- Health
- News.com.au
‘Crisis': Expert reveals secrets to how to get a flawless sleep
A new report has revealed the extent of Australia's silent sleep epidemic, with one expert offering simple fixes for the nation's most common sleeping difficulties. The Great Aussie Wake-Up, commissioned by Holiday Inn Express, found that 91 per cent of Australians struggle to fall or stay asleep in a typical week, and 93 per cent regularly wake up too early. Sleep expert Olivia Arezzolo said the research showed the issue had progressed from a problem to a crisis. But she said three core controllable elements could be implemented to form the foundation for good sleep. 'When you look at the biomechanics of the circadian rhythm, there are key factors which control it,' she said. 'Light is one, eating is another, and temperature is another.
Before adding the nice-to-haves, you need to get the essentials right first.' In terms of food, Ms Arezzolo stressed the importance of having breakfast and warned against all too common late night snacking. 'I think a really big factor which is often overlooked, is there's this massive growth in intermittent fasting,' she said. 'It's one of the biggest trends of 2025 and this is meaning that a lot of Gen Z, but also just overall Aussies, are skipping breakfast. 
 'The stat from the Holiday Inn research was that 76 per cent of Aussies are losing part of their morning routine and one in four are not eating breakfast. 'Breakfast is absolutely critical for circadian rhythm alignment. I'm sure you've heard that term with reference to light and temperature, but eating is also a regulator of the circadian rhythm.
 'It essentially anchors the body clock. So in order to fall asleep with ease in the evening, we need to be having breakfast within the first hour of being awake.' Ms Arezzolo said you ideally want three hours in between your last meal of the day and bedtime. For coffee it was a minimum of eight hours. 'I have a 2pm absolute latest cut-off time (for coffee), but ideally, you want nothing after 12 o'clock, especially if you're struggling to sleep.' For light Ms Arezzolo recommended getting 20 minutes of light within 30 minutes of waking and staying away from blue light producing screens close to bedtime. 'Like eating, light is a factor controlling the circadian rhythm. 
 'Essentially, if you're exposed to blue light in the evening, then you have the suppression of melatonin, which is your key sleep hormone to fall and stay asleep. 'This is akin to having a coffee before bed. As soon as you have that blue light enter your eyes, you have the biological signals to remain alert and awake.' 
 Another key finding of the report was an overreliance on the snooze button with more than half (52 per cent) of Australians hitting snooze every morning. Gen Z were among the worst offenders, with a massive 70 per cent regularly hitting the button – and one in ten tapping snooze at least 120 times a month. 'When you're hitting the snooze button regularly, every time the alarm goes off, you get a spike in your stress hormone cortisol,' Ms Arezzolo said. 'Too much cortisol leads to chronic states of anxiety, burnout, having that 'wired but tired feeling', being unable to sleep, and particularly 3am wakings. 'You're essentially setting your nervous system up to be on overdrive from the moment you wake up simply by pressing the snooze button, not just once, but multiple times. So that one is definitely alarming. Pardon the pun.' Ms Arezzolo said in the course of her regular life, people are constantly asking her to fix their sleep however they tend to focus on alternative aids rather than focusing on the essentials. 'I'm like, 'okay, but tell me about your mornings and tell me about your evenings. What are you doing just before you're waking up and just before you're going to sleep? What are you doing just when you're waking up? Do you have the foundations right'? 
And nine times out of 10, they don't. 'You can't overlook these and then just pick and choose which sleep strategies you want to employ because you prefer that. It doesn't work like that.
It's biology. 'Circadian rhythm is controlled by light, temperature and eating. So you have to get these things right.'
Irish Times
18-07-2025
- General
- Irish Times
Brianna Parkins: People who get up early in the morning for no reason are a menace to society
I am deep in enemy territory. Surrounded by supporters of the very regime I've been railing against for years: the menace to society that is people who get up early in the morning for no good reason. When I first moved to Ireland I had jet lag. They say you need one day per timezone to get over it. I had just jumped nine. By day three I was so tired I could smell colours. My body was a cranky toddler that drifted off to sleep in the car and came to screaming in a pram being pushed around an Aldi . I fought off the desperate and dragging need to sleep, going to bed later in a bid to reset myself. But I shouldn't have bothered my hole. My circadian rhythm was way off . It didn't matter if I slept at 7pm or 1am, my eyes would spring open at 4am without fail, and I would be ready to greet the day in Dublin . Except my new city wasn't ready to greet me. READ MORE My plan was to pretend to be a morning person, get up, get a coffee and walk around the streets. Cafes open from around 6am in Sydney or even earlier. I'd just wait two hours and watch the sun rise, beverage in hand. Then I discovered the sun wouldn't show itself properly until 9am in winter and no cafe except the closest Starbucks would open until 7.30am (the Sydney equivalent of noon). So I waited, and as I made my way through the streets of Ringsend , which were empty enough to make me feel I'd survived an apocalypse, I felt profound joy. Finally I had found my people. I had found a culture that didn't compel people to leap out of bed predawn. I saw tradespeople going to work at 8am or sometimes 9am; in Australia the heat has most on site between 5am and 7am. My new boss told me to show up at 10am. Brunch – the meal that's meant to come between breakfast and lunch – was being offered at 2pm. All this would have been unthinkable just a short time and a long plane ride ago. Ireland does have a decent number of early risers who do so out of choice and not work requirements. The sea swimmers who like to slice through Dublin Bay while it looks like glass. Parents of small children who have too much inconvenient guilt about drugging them. Nuns. Runners. Busy mothers who just want 'one bloody hour of quiet to themselves before everybody wakes up, if that's not too much to ask'. [ Moving to another country is hard. You're not failing if you're not living up to a filtered social media standard Opens in new window ] But you don't catch them banging on about it. It's very much a case of 'your body, your choice'. They're happy in their way but they won't attempt to proselytise you. Sadly, my partner has farming child trauma and believes that if you get up at 8am a man in wellies will come stand by your bed and tut 'sure half the day is gone' at you in shame. But even he enjoys an occasional lie-in. A morning safe from being ripped from the warm blankets and the soft bed, where it is so, so cozy and you are so, so comfy. When I moved back to Australia I realised the false supremacy of morning people had taken my beloved country to new extremes. It's become an influencer trend after Covid to take photos at Bondi or any beach at sunrise, doing something that could easily be done at any point of the day – like running or walking. Or wearing tights. The problem with morning people is that they assign moral value to what happens to be their natural preference. Which you never catch night people doing, oddly. Depriving yourself of sleep is not labelled performative productiveness – 'it's a mindset for success'. The Puritans would have hated TikTok , but they would have loved the early morning propaganda being spread on it. Instead of leaving early mornings for the Protestants (like my dad), we have let them become the drag impersonation of work ethic. Getting up and journaling at 6am is seen as self-discipline, but writing things in a diary at 2am is a cry for help. Working into the night is bad time management even if those are your most productive and creative hours. But waking up four hours before you have to work to faff around is not. It's a marketing battle, and we are letting the morning people win. Just as I cannot be brilliant at breakfast, a person who wakes up at 5am every day will be no craic at midnight. But who would you rather have at your wedding?
Medical News Today
15-07-2025
- Health
- Medical News Today
Eating late in the evening could make blood sugar control harder for the body
Our bodies process food differently depending on the time of day, with metabolism generally more active in the late eating is linked to obesity and heart disease, its exact effects on glucose metabolism and the role of genetics are still unclear.A new twin study from Germany now offers fresh insight into how meal timing interacts with our internal clocks and overall circadian system is a complex 24-hour timekeeping system that controls behaviour and metabolism through a central clock in the brain and additional clocks in organs such as the liver and of this system, our metabolism responds differently depending on when we eat, resulting in daily variations in glucose processing and hormone release after intake itself serves as an important signal that helps align our internal at times that are out of sync with the natural light-dark cycle, for example, when working night shifts, can disrupt these internal clocks and lead to adverse metabolic at the German Institute of Human Nutrition Potsdam-Rehbrücke (DIfE) have recently investigated the link between blood sugar metabolism and evening eating times using data from a twin study conducted in 2009– findings are published in the journal do we calculate circadian rhythms?Earlier research has shown that consuming meals late at night is linked to a higher risk of obesity and heart we still do not fully understand how meal timing interacts with a person's individual circadian rhythm and affects glucose metabolism and diabetes addition, the specific mechanisms behind when and why people eat remain unclear, as eating habits are shaped by a mix of cultural, situational, genetic and other biological timing of food intake in relation to a person's biological daily rhythm can be assessed by looking at the gap between mealtime and the midpoint of sleep midpoint refers to the time exactly halfway between falling asleep and waking up, and it indicates a person's chronotype, that is, whether they tend to be an early bird or a night late-night eating affects insulin sensitivityThe NUGAT study was carried out between 2009 and 2010 at the German Institute of Human Nutrition Potsdam-Rehbrücke (DIfE).To recruit participants, researchers used a twin registry (HealthTwiSt, Berlin, Germany) and public advertisements. In total, 92 individuals (46 pairs of identical and fraternal twins) took the twins completed two nutritional interventions during the study, these interventions were not relevant to the results discussed participants underwent comprehensive metabolic assessments, which included physical exams, medical history reviews, body measurements, and glucose tolerance tests. Their individual chronotypes were identified using a addition, each participant kept handwritten food diaries over 5 consecutive days (3 weekdays and 2 weekend days), recording the start and end times of each meal along with details on the type and quantity of food approach helped capture a realistic picture of their usual eating the analysis indicated that people who tended to have their final meal later in the day and closer to bedtime also had less effective glucose (blood sugar) metabolism at the end of the day, as they had lower insulin may suggest that better regulating our meal times may help maintain our metabolic you avoid eating late in the evening?Destini Moody, RD, CSSD, LD, registered dietitian at Top Nutrition Coaching, not involved in this research, reviewed the study and spoke to Medical News Today about its findings.'In general, I'm skeptical about adjusting the timing of one's eating in the hopes of controlling weight or blood sugar unless you are diabetic,' Moody told us.'My colleague and I used to joke that your digestive system doesn't work in shifts, meaning it doesn't 'clock out' after a certain time of day and decide to start storing everything as fat,' she added.'While it's well known that eating timing and meal composition is critical for controlling blood sugar and insulin action in those with diabetes, this study was performed on healthy individuals with normal pancreatic function and no other metabolic disturbances. Even without diabetes, those with metabolic syndrome should be careful about their level of insulin resistance, but none of the subjects fell under this category either given their BMI and waist circumference. The average age of subjects was also 32, which is relatively young.'– Destini Moody, RD, CSSD, LD'As far as the genetic component of how eating timing influences insulin sensitivity, this is a mixed bag, [too]' Moody further noted. 'On the one hand, it's an interesting finding, but on the other hand, genetic factors are difficult to detect and control.''In general, blood sugar variations are a natural part of digestion and metabolism, and I would urge the public to refrain from stressing about the effects food may have on their blood sugar unless they have metabolic ailments like type 2 diabetes,' she she did emphasize that it is always important to pay attention to how much fiber we ingest, and how much of it comes from refined explained:'Foods with added sugars, that have been made with refined grains, and are generally low in fiber will raise blood sugar quickly and send it crashing back down due to a rebound effect. This tends to make people even hungrier and even cause fatigue, which is why you feel sleepy after having meals high in these types of carbs. Luckily, eating whole grains and high fibers fruits and vegetables along with lean protein can not only help mitigate this effect, but often results in a healthier diet overall that helps prevent the risk of chronic disease.'
