How Much Caffeine You Should Actually Have—and When
Figure out the right amount of caffeine to boost alertness without disrupting your sleep
Figure out the right amount of caffeine to boost alertness without disrupting your sleep
Caffeine can give us a boost, but too much can mess with our sleep and make us feel jittery. So how do we know what’s the right amount?
Generally, government and health groups recommend that healthy adults consume no more than 400 milligrams of caffeine a day. That comes out to about four, 8-ounce cups of coffee, says Jennifer Temple, a professor of exercise and nutrition sciences at University at Buffalo School of Public Health and Health Professions.
(No, that 20-ounce Starbucks Venti doesn’t count as one cup of coffee.)
And believe it or not, we are doing pretty well on this target. The average American adult consumes about 200 milligrams of caffeine a day and in Europe, it is 270 milligrams, according to a 2017 review study.
But not everyone is optimising their caffeine intake to maximise how it can help them—by sharpening concentration for work or giving them a boost before a run—without hurting their sleep or overall health.
Here’s how to think strategically about getting the most out of your daily dose.
Caffeine can help you focus and keep you alert.
About 100 to 150 milligrams—or one to 1.5 cups of coffee—is a ballpark amount that will deliver a boost, says Astrid Nehlig, an emeritus research director at the French National Institute of Health and Medical Research, who has studied caffeine’s impact on brain activity, though it varies from person to person.
The effects generally kick in about five minutes after consumption and increase to become optimal for between roughly 15 and 120 minutes, Nehlig says.
Caffeine has been linked to physical benefits, too. People walked more on days they drank coffee than on days they didn’t, according to a 2023 study of 100 people in the New England Journal of Medicine. Participants took an average of 1,000 more steps on days when they drank caffeinated coffee than when they didn’t.
Other studies have suggested that caffeine can sometimes help us work out harder, such as when we have it before high-endurance exercise like long runs or swims, or sports that require a sustained effort, like soccer, Nehlig says.
The same boost hasn’t been found with shorter efforts, such as a sprint. Caffeine doesn’t act directly on muscles but rather reduces your rate of perceived exertion and the time it takes you to feel exhausted.
Caffeine’s main negative for your health is that it can disrupt your sleep.
The NEJM study that found that people walk more on days when they drink caffeine also found a downside. On days when study participants could drink as much caffeinated coffee as they wanted, they slept on average 30 minutes less than on days they didn’t drink any.
The impact on sleep varies greatly depending on how fast you metabolise caffeine, says Gregory Marcus, a cardiologist and professor of medicine at University of California, San Francisco and first author of the NEJM study.
On average, it takes about 4.5 hours for half of the caffeine consumed to pass through your system. However, genetic differences make some people metabolise it slowly or quickly, doctors and researchers say. The population is roughly split between fast and slow metabolisers.
The sleeping and walking study tested whether participants were slow or fast metabolisers of coffee. Those that were slow metabolisers slept nearly an hour less on the nights they drank caffeinated coffee, while the fast metabolisers didn’t experience any impact on sleep.
The best source of caffeine is unsweetened coffee or tea, says Dr. Frank Hu, professor of nutrition and epidemiology at Harvard T.H. Chan School of Public Health. These drinks have other beneficial ingredients, such as polyphenols, which have antioxidant effects which reduce inflammation.
The caffeine content in coffee and tea can vary, but soda can’t have more than 71 milligrams per 12 ounces, per Food and Drug Administration regulations.
Adults get most of their caffeine from coffee, but the market for energy drinks is growing. Pay extra attention to the caffeine in these drinks, because some contain very high levels.
Getting caffeine from soda or energy or sports drinks makes it more likely you are also getting a high dose of sugar and empty calories, says Hu.
Kids under 12 should avoid caffeine, while 12- to 18-year-olds should have no more than 100 milligrams a day, according to the American Academy of Pediatrics. Pregnant women are advised to have no more than 200 milligrams of caffeine a day.
People with chronic conditions like high blood pressure, diabetes or heart disease might want to be more cautious about their caffeine consumption, Hu adds. The NEJM study found that on the days when participants consumed caffeine, they had more abnormal heart rhythms in the lower chamber of the heart, which is associated with a greater risk of developing heart failure.
And people who get migraine headaches should try to drink no more than 100 milligrams of caffeine a day, the equivalent of a mug of coffee, says Dr. Amaal Starling, a headache specialist and neurologist at Mayo Clinic in Scottsdale, Ariz. She advises her patients who have daily or severe headaches not to drink any caffeinated beverages or switch to decaffeinated coffee.
As tariffs bite, Sydney’s MAISON de SABRÉ is pushing deeper into the US, holding firm on pricing and proving that resilience in luxury means more than survival.
Early indications from several big regional real-estate boards suggest March was overall another down month.
Can its real-estate market continue to rise amid stock-market turmoil?
MANALAPAN, FLA.— The Deal-Closer. That’s what real-estate agent Jack Elkins jokingly calls the Hinckley picnic boat he docks on the Intracoastal Waterway in the Florida community of Manalapan.
From the road, many of Manalapan’s mansions are shrouded by plantings and foliage, but they are clearly visible from the water, Elkins explained. A boat ride is often the best way to show properties to the wealthy buyers now flocking to the tiny town.
On a recent afternoon, Elkins cruised down the Intracoastal in the The Deal-Closer, passing mansion after mansion, most with their own docks. “When I was a little kid, almost all of this was jungle,” said Elkins, 46, who spent much of his childhood in the area. “There were foxes and parrots and all these wild animals.”
Manalapan, a roughly 2.4-square-mile town with a population of about 400, is just south of glitzier Palm Beach.
While Manalapan has long drawn moneyed residents such as the singer Billy Joel, it has historically lacked the prestige—and price tags—of Palm Beach. That has changed dramatically over the past five years, however, thanks to a series of major home sales.
In 2022, for example, Oracle billionaire Larry Ellison paid $173 million for a historic Manalapan estate. And David MacNeil, the founder of the automotive-accessories manufacturer WeatherTech, has spent a combined $94 million over the past year on a pair of neighboring sites, with plans to build a megamansion there.
“People like Larry Ellison and David MacNeil, these individuals can afford to buy real estate anywhere in the world,” said local real-estate agent Nick Malinosky of Douglas Elliman . “Manalapan is not a second choice for them. It’s their first choice.”
On South Ocean Boulevard, Manalapan’s most affluent corridor, about 21 homes have traded for more than $20 million each since 2020. At least six have sold for $40 million or more, up from only one in that price range during the previous five years.
In 2021, eBay billionaire Jeffrey Skoll bought an ocean-to-Intracoastal estate for $89.93 million, while Joel’s longtime home sold last year for $42.6 million.
Now, however, it is unclear whether Manalapan’s hot streak can continue. Like luxury markets across the country, the town is contending with stock-market turmoil and the fallout from President Trump’s tariffs.
Like many Manalapan residents, local developer Stewart Satter, who is listing a yet-to-be-built spec home for $285 million, is a Trump supporter. During the 2024 election, Satter flew a giant Trump flag above the site.
But tariffs have “created a tremendous amount of uncertainty at the minimum, and that is not good for business,” Satter said. “It’s not good for real estate. People say, ‘Let’s wait. We’re not going to buy a house, we’re not going to build a house.’”
Elkins’ cuddly Native American Indian Dog, Bear, lounged on The Deal-Closer’s blue-and-white-striped seats as the boat zipped along the Intracoastal, passing glassy modern mansions and traditional Mediterranean estates.
To catch a glimpse of Ellison’s roughly 16-acre oceanfront estate, Elkins guided the Hinckley through the Boynton Inlet into the choppy Atlantic, where the sandy beach in front of Ellison’s property was visible.
Known as Gemini, the gargantuan mansion was once owned by the late publishing magnate William B. Ziff Jr., who brought in large plantings and trees from South America for the landscaping.
“When I was a little kid, barges were going by our house with these huge trees,” Elkins recalled.
Ellison has approved plans to add more homes to the estate. He also paid about $277 million last year for Manalapan’s Eau Palm Beach Resort & Spa, home to the members-only La Coquille Club, and talk is rife about how Ellison might upgrade the property. Ellison didn’t respond to requests for comment.
It’s a strange feeling, Elkins said, to see Manalapan hit the big time.
Before Covid, the town was often confused with its namesake: Manalapan, N.J. Tiny compared with Palm Beach, Manalapan developed much more slowly than its famous neighbour. It lacks the commercial infrastructure of Palm Beach, and its low-density zoning has kept it largely free of major condos or resorts.
When Satter, the developer, bought four empty lots in Manalapan in 2005, parts of the town looked like “just a mess of woods,” said his wife, Susan Satter. “I said, ‘Is this really how we want to invest our money?’”
Over the next decade, her husband built spec homes on three of the lots and sold them for a significant profit. He kept one, building a mansion there for himself and his wife.
“I thought I’d discovered a really special place,” said Stewart, who tested products for Walmart before turning to spec-home development. “If I had known what was going to happen, obviously, in the rear view mirror, I would have bought the whole town.”
The buyers of Satter’s projects include Ron and Cindy McMackin, who paid roughly $39 million in 2020 for a roughly 15,500-square-foot waterfront house with six bedrooms, then expanded it.
The couple, founders of the mechanical subcontracting company Pan-Pacific Mechanical, had relocated from Hawaii to South Florida during COVID.
“We knew nothing about Manalapan when we moved here,” said Ron, 78. He and Cindy were in the process of moving into a Palm Beach property they owned when their real-estate agent, Lawrence Moens , called. The actor Sylvester Stallone was searching for a home amid the Covid-induced real-estate frenzy, and wanted to see their house.
Before they knew it, they had agreed to sell to the “Rocky” star for $35.375 million, 33% more than the $26.65 million they had paid two years earlier.
This left them without a house. It was slim pickings in Palm Beach, and with five children, they needed plenty of space. Moens suggested Manalapan. At the time, the less-flashy choice was surprising to some of their Palm Beach friends. “I did hear a couple of times from people after that, ‘Why would Lawrence take the McMackins to Manalapan?’” said Ron.
But the McMackins love that it is quieter than Palm Beach, with less traffic. The couple have Sunday dinners with their neighbours, and Cindy has a small group of girlfriends who call themselves the “Manalapan mafia.” The McMackins like it so much that they are building a new, larger home along the same stretch.
Food-service entrepreneur Bob Carlucci and his wife, Aileen Carlucci, paid $11.63 million in 2020 for a roughly 13,000-square-foot Manalapan mansion on the Intracoastal, with a small beach house on the ocean. They are happy to have “discovered Manalapan early, ” Bob said.
Many buyers are tearing down older homes to build new mansions, Malinosky said. Before COVID, Manalapan was seen as more of a vacation destination, so buyers weren’t as choosy. Now that many are seeking full-time homes, however, “they want to make sure that it has the spa, it’s got the 12-car garage, it’s got the fitness centre, it’s got the wellness centre.”
Another prized amenity is a tunnel that runs underneath Highway A1A. Portions of the town are on a barrier island, and some homes sit on the ocean, requiring residents to cross the busy road to reach their docks on the Intracoastal.
Other estates are on the Intracoastal but have small beachhouses on the ocean. A tunnel allows residents to easily go from one side to the other.
Construction of these tunnels has become a rare point of contention between residents. In January, one couple asked the town commission to stop their neighbors from digging under the highway during the tourist season, claiming it was causing traffic to back up.
Building on the coast comes with challenges. Florida building code now requires roofs, windows and doors in high-risk areas to withstand winds of up to 170 miles an hour, according to builder Robert Burrage, who is building MacNeil’s home and four others in Manalapan.
Satter said the property insurance on his personal residence in Manalapan doesn’t include coverage for hurricane damage because it was too expensive. In addition to the annual premium, which was about $150,000 a year, he would have faced a deductible on hurricane damage of about 10% of the assessed value of the house.
He isn’t concerned with rising sea-levels, however. “When I bought my first oceanfront lot, my late father-in-law said, ‘What the hell are you doing? Don’t you know about global warming?’” Satter said. “I sold it at a huge number [in 2016] and made a lot of money. It’s been sold again and again and again—and the water hasn’t done anything.”
Manalapan’s proximity to Mar-a-Lago has added to its popularity since Trump’s election to a second term, Malinosky said. Many residents support Trump. In the McMackins’ home, a bedazzled MAGA purse hangs in Cindy’s closet and a photo book in the living room shows her attending a Trump event at Mar-a-Lago, where they are members.
But the trade war and stock-market volatility have injected uncertainty into the real-estate market.
Until recently, Hamptons home builder Joe Farrell was considering paying more than $30 million for a building site in Manalapan, he said. He has decided to hold off on any acquisitions for now, however, because of the tariffs and resulting stock-market fallout.
“The market seems to still be pretty good, but people are maybe a little more cautious about parting ways with liquidity,” Farrell said. “I want to see things stabilize before I commit to that kind of capital outlay.”
Elkins said one of his clients considered backing out of a $10 million deal over the last few weeks on Point Manalapan, but decided to move ahead to avoid forfeiting the deposit.
Malinosky said he still sees significant demand for big-ticket properties in Manalapan, especially since many wealthy people are taking money out of the stock market. He said he has closed more than $150 million in deals in the greater Palm Beach area over the past two weeks.
Even with the uncertainty, “there is no shortage of buyers that will spend $100 million right now in Manalapan,” he said.
Shelly Newman, an agent with the Corcoran Group, said she recently sold a piece of land to a spec-home developer for $25 million. And the McMackins are moving ahead with plans to complete their new house, though tariffs have been “the talk of the town,” Ron said.
“I do have a stock portfolio and it is down,” he said. “But I don’t let that affect what I’m doing. We’re very fortunate with resources.”
While Satter agrees with efforts to bring manufacturing back to the U.S., he said he has been blindsided by the extent of the trade war. “I’m not sure about how they’re rolling it out,” he said.
A handful of potential buyers have expressed interest in his $285 million listing, he said, but he realizes the prospective buyer pool is tiny. “There are going to be three or four people who ultimately show real interest and have the capacity to pull the trigger,” he said.
Ultimately, he said he isn’t too worried about the prospects for sale, since he can afford to sit on the property long-term.
Still, real-estate agents said Satter’s property and others may be priced too aggressively, even without tariffs.
British hedge-fund billionaire Chris Rokos is listing his 3-acre Manalapan estate for $150 million, more than triple what he paid for it in 2017. And real-estate investor Vivian Dimond recently cut the price of a Manalapan home by $14.5 million, to $64.5 million. It’s been on the market since September 2024.
For some Manalapan residents, home values are beside the point. Bob and Aileen Carlucci, for example, have no intention of moving.
“We look at each other and we say. ‘This is it,’” Bob said. “You can’t get anything better, we don’t believe—in this country, at least.”
Some carefully chosen accessories can speak volumes in a gentleman’s casual attire.
President Donald Trump’s imposition of tariffs on trading partners have moved analysts to reduce forecasts for U.S. companies. Many stocks look vulnerable to declines, while some seem relatively immune. Since the start of the year, analysts’ expectations for aggregate first-quarter sales of S&P 500 component companies have dropped about 0.4%, according to FactSet. The hundreds …
Continue reading “Health Is Wealth When Tariffs Are Denting Profit Forecasts”