Have you ever noticed how some people bounce out of bed after just a few hours of sleep, while others can barely function without a solid eight hours?

Take Margaret Thatcher, for example. The former British prime minister was known for sleeping just four hours a night. She worked late, rose early, and seemed to thrive on little sleep.

But for most of us, that kind of sleep schedule would be disastrous. We’d be groggy, unfocused, and reaching for sugary snacks and caffeinated drinks by mid-morning.

So why do some people seem to need less sleep than others? It’s a question that’s fascinated scientists for years. Here’s what we know so far.

Natural short sleepers

There is a small group of people who don’t need much sleep. We call them natural short sleepers. They can function perfectly well on just four to six hours of sleep each night, often for their entire lives.

Generally they don’t feel tired, they don’t nap, and they don’t suffer the usual negative consequences of sleep deprivation. Scientists call this the natural short sleep phenotype – a biological trait that allows people to get all the benefits of sleep in less time.

In 2010 researchers discovered genetic mutations that help explain this phenomenon. Natural short sleepers carry rare variants in certain genes, which seem to make their sleep more efficient.

More recently, a 2025 study assessed a woman in her 70s with one of these rare mutations. Despite sleeping just six hours a night for most of her life, she remained physically healthy, mentally sharp, and led a full, active life. Her body, it seems, was simply wired to need less sleep.

We’re still learning about how common these genetic mutations are and why they occur.

Not everyone who sleeps less is a natural short sleeper

But here’s the catch: most people who think they’re natural short sleepers aren’t. They’re just chronically sleep-deprived. Often, their short sleep is due to long work hours, social commitments, or a belief sleeping less is a sign of strength or productivity.

In today’s hustle culture, it’s common to hear people boast about getting by on only a few hours of sleep. But for the average person, that’s not sustainable.

The effects of short sleep build up over time, creating what’s known as a “sleep debt”. This can lead to poor concentration, mood swings, micro-sleeps (brief lapses into sleep), reduced performance and even long-term health risks. For example, short sleep has been linked to an increased risk of obesity, diabetes, high blood pressure and cardiovascular disease (heart disease and stroke).

The weekend catch-up dilemma

To make up for lost sleep during the week, many people try to “catch up” on weekends.

This can help repay some of the sleep debt that has accumulated in the short term. Research suggests getting one to two extra hours of sleep on the weekend or taking naps when possible may help reduce the negative effects of short sleep.

However, it’s not a perfect fix. Weekend catch-up sleep and naps may not fully resolve sleep debt. The topic remains one of ongoing scientific debate.

A recent large study suggested weekend catch-up sleep may not offset the cardiovascular risks associated with chronic short sleep.

What’s more, large swings in sleep timing can disrupt your body’s internal clock, and sleeping in too much on weekends may make it harder to fall asleep on Sunday night, which can mean starting the working week less rested.

Increasing evidence indicates repeated cycles of irregular sleep may have an important influence on general health and the risk of early death, potentially even more so than how long we sleep for.

Ultimately, while moderate catch-up sleep might offer some benefits, it’s no substitute for consistent, high-quality sleep throughout the week. That said, maintaining such regularity can be particularly challenging for people with non-traditional schedules, such as shift workers.

So, was Thatcher a true natural short sleeper?

It’s hard to say. Some reports suggest she napped during the day in the back of a car between meetings. That could mean she was simply sleep-deprived and compensating for an accumulated sleep debt when she could.

Separate to whether someone is a natural short sleeper, there are a range of other reasons people may need more or less sleep than others. Factors such as age and underlying health conditions can significantly influence sleep requirements.

For example, older adults often experience changes in their circadian rhythms and are more likely to suffer from fragmented sleep due to conditions such as arthritis or cardiovascular disease.

Sleep needs vary from person to person, and while a lucky few can thrive on less, most of us need seven to nine hours a night to feel and function our best. If you’re regularly skimping on sleep and relying on weekends to catch up, it might be time to rethink your routine. After all, sleep isn’t a luxury – it’s a biological necessity.

Kelly Sansom, Research Associate, College of Medicine and Public Health, Flinders University; Research Associate, Centre for Healthy Ageing, Murdoch University and Peter Eastwood, Deputy Vice Chancellor, Research and Innovation, Murdoch University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Do you hate salad? It’s OK if you do, there are plenty of foods in the world, and lots of different ways to prepare them.

But given almost all of us don’t eat enough vegetables, even though most of us (81%) know eating more vegetables is a simple way to improve our health, you might want to try.

If this idea makes you miserable, fear not, with time and a little effort you can make friends with salad.

Why don’t I like salads?

It’s an unfortunate quirk of evolution that vegetables are so good for us but they aren’t all immediately tasty to all of us. We have evolved to enjoy the sweet or umami (savoury) taste of higher energy foods, because starvation is a more immediate risk than long-term health.

Vegetables aren’t particularly high energy but they are jam-packed with dietary fibre, vitamins and minerals, and health-promoting compounds called bioactives.

Those bioactives are part of the reason vegetables taste bitter. Plant bioactives, also called phytonutrients, are made by plants to protect themselves against environmental stress and predators. The very things that make plant foods bitter, are the things that make them good for us.

Unfortunately, bitter taste evolved to protect us from poisons, and possibly from over-eating one single plant food. So in a way, plant foods can taste like poison.

For some of us, this bitter sensing is particularly acute, and for others it isn’t so bad. This is partly due to our genes. Humans have at least 25 different receptors that detect bitterness, and we each have our own genetic combinations. So some people really, really taste some bitter compounds while others can barely detect them.

This means we don’t all have the same starting point when it comes to interacting with salads and veggies. So be patient with yourself. But the steps toward learning to like salads and veggies are the same regardless of your starting point.

It takes time

We can train our tastes because our genes and our receptors aren’t the end of the story. Repeat exposures to bitter foods can help us adapt over time. Repeat exposures help our brain learn that bitter vegetables aren’t posions.

And as we change what we eat, the enzymes and other proteins in our saliva change too. This changes how different compounds in food are broken down and detected by our taste buds. How exactly this works isn’t clear, but it’s similar to other behavioural cognitive training.

Add masking ingredients

The good news is we can use lots of great strategies to mask the bitterness of vegetables, and this positively reinforces our taste training.

Salt and fat can reduce the perception of bitterness, so adding seasoning and dressing can help make salads taste better instantly. You are probably thinking, “but don’t we need to reduce our salt and fat intake?” – yes, but you will get more nutritional bang-for-buck by reducing those in discretionary foods like cakes, biscuits, chips and desserts, not by trying to avoid them with your vegetables.

Adding heat with chillies or pepper can also help by acting as a decoy to the bitterness. Adding fruits to salads adds sweetness and juiciness, this can help improve the overall flavour and texture balance, increasing enjoyment.

Pairing foods you are learning to like with foods you already like can also help.

The options for salads are almost endless, if you don’t like the standard garden salad you were raised on, that’s OK, keep experimenting.

Experimenting with texture (for example chopping vegetables smaller or chunkier) can also help in finding your salad loves.

Challenge your biases

Challenging your biases can also help the salad situation. A phenomenon called the “unhealthy-tasty intuition” makes us assume tasty foods aren’t good for us, and that healthy foods will taste bad. Shaking that assumption off can help you enjoy your vegetables more.

When researchers labelled vegetables with taste-focused labels, priming subjects for an enjoyable taste, they were more likely to enjoy them compared to when they were told how healthy they were.

The bottom line

Vegetables are good for us, but we need to be patient and kind with ourselves when we start trying to eat more.

Try working with biology and brain, and not against them.

And hold back from judging yourself or other people if they don’t like the salads you do. We are all on a different point of our taste-training journey.

Emma Beckett, Senior Lecturer (Food Science and Human Nutrition), School of Environmental and Life Sciences, University of Newcastle

This article is republished from The Conversation under a Creative Commons license. Read the original article.