Latest news with #sunexposure
Fast Company
4 days ago
- Entertainment
- Fast Company
Jack Dorsey's new Sun Day app tells you exactly how long to tan before you burn
Twitter cofounder Jack Dorsey is back with a new app that tracks sun exposure and vitamin D levels. Sun Day uses location-based data to show the current UV index, the day's high, and additional details like cloud cover, sunrise, and sunset times. Users can choose their skin type from six options and indicate their clothing, such as 'light (shorts & t-shirt)', then manually toggle when they're in or out of the sun. Based on this input, the app calculates how long you can safely expose your skin before it begins to burn. That's an especially helpful feature for those like Dorsey, who mentioned in an X thread that he does not actually use sunscreen. no — jack (@jack) July 13, 2025 The app also tracks a user's estimated vitamin D intake while outdoors. After tapping the 'Track UV exposure' button to start a session, the app shows how much vitamin D was absorbed once the session ends. In future updates, additional factors like height, weight, and actual vitamin D blood levels may be included to improve the app's accuracy. This marks the second new app Dorsey has launched in a week. But this one may especially appeal to Gen Z, whose tanning obsession has sparked a trend of tracking UV exposure to optimize time spent basking in the sun. In 2025, the importance of sunscreen isn't lost on most. Google searches for 'best anti-ageing sunscreen' and 'UV damage prevention' have more than doubled over the past two years. Yet on TikTok and Instagram, tanning is back in vogue. Girls flaunt their bikini strap marks, share their tanning routines, and even create sun tattoos (aka skin damage). Some are faking it using blush, bronzer, or spray tans to mimic the sunkissed, or sunburnt, look. Others track the UV index to find the 'best' time to tan.
CNET
6 days ago
- Health
- CNET
This New App Wants to Help You Track Your Sun Exposure
The founder of Twitter, Jack Dorsey, has a bright idea that he's released as a beta app: Sun Day, for tracking your exposure to the sun. The app is free to testers and so far contains basic information such as sunrise, sunset and the UV index in order to assess a user's potential burn limit time and, as the app description says, "track your Vitamin D from the sun." Dorsey is currently testing UI updates and a solar noon notification, according to the app notes. In the app, users can describe the type of clothing they're wearing, such as shorts and T-shirts or swimwear, and Fitzpatrick skin type, which classifies how quickly you'll burn. People tend to think about sun exposure and protections like sunscreen most during the summer, when the sun is strongest and the days are long and when they're heading to the beach or out gardening, golfing or otherwise getting in quality sun time. The iOS app asks permissions to connect to some Apple Health data when the app is installed. Dorsey announced an iOS Test Flight app, Sun Day, on Sunday, with a post on X (former Twitter). Dorsey also recently released Bitchat, a private messaging client that uses Bluetooth as its communication platform. Although it's meant to be a secure, private app, some users have flagged Bitchat for potential security flaws that are still being tested.
Gizmodo
6 days ago
- Gizmodo
Jack Dorsey Drops His Second New App in a Week
Jack Dorsey is shipping. On Sunday, the Twitter co-founder shared a link on X (formerly Twitter) to a new app called Sun Day, which he claims helps users track their vitamin D intake. It's the second new app he's debuted in a week, and it's all thanks to the help of AI. Sun Day calculates how long users can safely soak up the sun before burning their skin using the UV index of the user's location, cloud cover, sunrise and sunset times, skin tone, and even what kind of clothes they're wearing. This feature is no doubt helpful to people like Dorsey, who casually mentions later in the thread that he does not use sunscreen. The app also tracks a user's time outdoors to supposedly estimate how much vitamin D they're absorbing. This is based on 'UV exposure using a multi-factor model based on scientific research,' according to the app's GitHub page. Just how accurate that model is remains unclear. Future updates will improve calculations with factors like height, weight, and the user's actual vitamin D blood levels. For now, anyone who is curious can try Sun Day themselves on iOS via TestFlight or poke around its code on GitHub. Like Dorsey's other recent 'weekend project,' BitChat, Sun Day was built using Goose, the AI coding assistant developed by Block, Dorsey's payments company. And both projects are part of a broader trend Dorsey seems into right now, 'vibe coding.' Vibe coding is a newish approach where developers rely heavily on AI assistants to generate and debug code using natural language prompts. This allows developers to focus more on the overall 'vibe' of what they're trying to accomplish with an app rather than the technical specifics of its code. The previous Sunday, Dorsey announced the beta launch of BitChat, a messaging app built for peer-to-peer conversations over Bluetooth mesh networks instead of the internet that does not require any phone numbers, emails, or any permanent IDs to function. '[B]itchat addresses the need for resilient, private communication that doesn't depend on centralized infrastructure,' Dorsey explained in a white paper published to his GitHub page. 'By leveraging Bluetooth Low Energy mesh networking, bitchat enables direct peer-to-peer messaging within physical proximity, with automatic message relay extending the effective range beyond direct Bluetooth connections.' But BitChat has already run into skepticism. In a recent blog post, Supernetworks CEO Alex Radocea pointed out a major flaw: the app does not currently have any real way to verify who a user is talking to. 'In cryptography, details matter,' Radocea wrote. 'A protocol that has the right vibes can have fundamental substance flaws that compromise everything it claims to protect.' Since the blog post, the app's GitHub page has added a warning stating that the app 'has not received external security review and may contain vulnerabilities and does not necessarily meet its stated security goals.' It's just a reminder that vibecoding might be a way for developers to brute-force their way to a functional product, but users might want to think twice before installing these apps and taking on the potential security risks.
The Verge
6 days ago
- The Verge
Now Jack Dorsey has built an app to track your vitamin D
Twitter co-founder Jack Dorsey has released a new app that tracks your sun exposure and vitamin D levels. It's his second app in a week, after last weekend's encrypted peer-to-peer messaging app Bitchat. Sun Day is available now for iOS via TestFlight, and the code for the project is available on GitHub. The app uses location-based data to display your local UV index and sunlight hours. You can detail your skin type and clothing level, then manually toggle when you're in and out of the sun and the app will track your rough vitamin D levels for the day, along with how long you can be in direct sunlight without burning. Dorsey says he's 'learning' through his recent weekend coding projects, which he's developing using the open-source AI coding tool Goose. It and similar vibe coding tools are one of the next key battlegrounds for tech's AI giants — just last week a $3 billion deal for OpenAI to buy AI coding tool Windsurf fell through, as Google swooped in to hire Windsurf's CEO and top talent onto its DeepMind team.
Khaleej Times
7 days ago
- Health
- Khaleej Times
What are the health benefits of moderate sun exposure?
Q: I've heard two conflicting things about sun exposure — that you should avoid it and that it's good for you. What should I believe? A: For decades, many doctors have said that less is more when it comes to sun exposure. Ultraviolet light from the sun can age the skin and cause skin cancer, and people can get vitamin D from food or supplements instead. But in recent years, some scientists have questioned this thinking after research suggested that moderate sun exposure may, at least in certain contexts, have some benefits. And that vitamin D supplements may not always be a good substitute. 'The 'never go outside without S.P.F. 50' approach treated sun exposure as if it were universally harmful,' said Dr Lucy McBride, an internal medicine physician in Washington, D.C. But 'moderate, thoughtful sun exposure,' in accordance with your risk factors, she added, 'may offer benefits we're still discovering'. Sunshine has a bright side It's undeniable that the sun's rays can damage your skin in ways that result in premature skin ageing and cancer, said Dr Elizabeth Ko, an internal medicine physician at UCLA Health who has written about the health effects of sun exposure. But researchers have also identified a handful of potential, if limited, associations between sun exposure and health benefits. Research has found that spending more time in the sun is associated with lower blood pressure. Blood pressure tends to be higher in the winter than in the summer, said Dr Richard Weller, a dermatologist and researcher at the University of Edinburgh, and heart problems are more common then, too. One study found that people who reported more sunlight exposure were less likely to develop heart failure. Researchers aren't sure why sunlight might improve heart health, but they do know that it causes the skin to release a gas called nitric oxide, which relaxes blood vessels and reduces blood pressure, Dr Weller said. Some researchers have wondered if that could result in a longer life. In a 2014 study that followed nearly 30,000 Swedish women for 20 years, scientists found that those who avoided the sun were twice as likely to die during that time period as those most exposed to sunlight — even though the sun-seeking women were more likely to be diagnosed with melanoma, a deadly form of skin cancer. Sunlight may also help support the immune system by controlling inflammation and immune cells. In one small study of 11 multiple sclerosis patients, researchers found that ultraviolet B light activated certain immune cells that calmed inflammation and eased symptoms. Other research has shown that UV light exposure can improve symptoms in people with eczema, psoriasis and other immune-related conditions, Dr. McBride said. Basking in the sun could also make you happier, Dr Ko added. Some studies suggest that exposure to UV light can increase blood levels of serotonin, a chemical that helps regulate mood. Of course, it's hard to to tell if the sunlight itself is responsible for these health benefits, Dr McBride said. People who are exposed to a lot of sunlight may also engage in more physical activity and spend more time in nature than other people do, she said, all of which may independently boost mood and physical health. It may not (just) be the vitamin D A well-known benefit of sun exposure is that it triggers the body to produce vitamin D, which helps to build and maintain bones. Past observational research has linked low levels of vitamin D with increased risks of certain conditions like heart disease, Type 2 diabetes and colorectal cancer. Would ingesting vitamin D from fortified foods or supplements reduce the risk of these conditions, eliminating the need for potentially harmful sun exposure? Large clinical trials over the past several years have not confirmed this, Dr Weller said. In a 2019 clinical trial, researchers concluded that taking vitamin D supplements did not reduce the likelihood of developing Type 2 diabetes in about 2,400 adults who had risk factors for the condition. And a 2020 trial of about 26,000 adults in the United States found that vitamin D supplements did not reduce the risk of developing cancer or cardiovascular problems, nor did it reduce the overall risk of death over the study period, which averaged about five years. These studies, along with those showing the immune and blood pressure benefits of sunshine, suggest that sunlight may benefit us beyond just vitamin D production, Dr McBride said. Don't ditch your sunscreen The research on sunshine's potential benefits is still quite limited, so it's hard to know how to interpret or apply it, or how to square it with the risks for skin cancer, Dr McBride said. And you shouldn't stop using sun protection altogether, she said. Dr Ko recommended avoiding direct sun exposure between 10am and 2pm, 'when the rays are the brightest and strongest'. If you can't do that, wear sunscreen or other protection such as wide-brimmed hats or sun-protective clothing. Ultimately, it may make sense to consider sunlight's potential benefits along with its harms, Dr McBride said. 'Skin cancer remains a serious threat,' she said. 'But it is about moving beyond fear-based, one-size-fits-all messaging.'
