Zonked, frazzled, drained, pooped, knackered, running on fumes – or just totally exhausted. In much the same way that the Shona-speaking people of Zimbabwe have a dozen verbs for walking, our modern vocabulary seems to have developed 20 ways of explaining that we are quite tired, most of the time. But is there anything about 21st-century life – our screen addictions, side-hustle culture or always-on mindsets – that means we are more tired, or are we just noticing it more? And when should you start to worry? “The simple answer is that we need to distinguish between tiredness and fatigue,” says Prof Russell Foster, head of the Sleep and Circadian Neuroscience Institute at the University of Oxford. “Tiredness is cured by getting enough sleep; fatigue is not, and is typically a marker of an underlying health condition. So if you’re getting enough sleep but waking up feeling chronically lethargic and unable to function properly, you need to see your GP.” Those issues tend to appear alongside other symptoms, says Dr Luke Powles, associate clinical director at Bupa Health Clinics. “Anaemia – when you don’t have enough red blood cells or haemoglobin for your body’s needs – can cause weakness, or shortness of breath, while diabetes can cause thirst and weight loss. An underactive thyroid gland – which can mean that your metabolic processes aren’t being regulated properly – often causes weakness and fatigue, but can present alongside weight gain and depression.” But what if you’re just … tired? Maybe you are getting seven to eight hours’ sleep – or trying to – but you are worried that restlessness during the night, or some dysfunction in your circadian rhythm, is leaving you bleary-eyed and weary during the day? Well, the first thing to understand is that the traditional recommendations are often too simplistic. “Everybody’s neurotic about their eight hours these days, but the studies take averages,” says Foster. “A healthy range for sleep time might be as few as six hours or as many as 10, or 10 and a half. Yes, various studies have said if you get more or less than eight you’re going to have a reduced life expectancy, but many of those studies didn’t look at the health status of the participants. “If you’ve got fatigue, which is a marker of poor health, you’ll probably sleep more – and in the same way, if you have short sleep, that could be due to a whole range of things, not least intractable pain. So not all of the studies are helpful.” One good bit of advice, then, is that if you feel foggy during the day, go to bed a bit earlier. If you hit a point where the hours of sleep you are getting are making your days more bearable, you will probably find a way to stick with it. But what if you suspect that time in bed alone isn’t the problem? “The thing to understand is that many people don’t have a sleep problem – they have a stress or an anxiety problem,” says Foster. “There’s a condition called sleep anxiety, which happens when people are so worried about not getting to sleep or about waking up in the middle of the night that it affects their sleep. And what most people don’t know is that waking up in the middle of the night is perfectly normal – it’s the default position of all mammalian sleep, whether you’re conscious of it or not. And when you tell people this, they think: ‘Oh my God, I’m not abnormal. If I just stay relaxed and keep the lights low, I will almost certainly fall back to sleep.’ And that often works.” If you are interested in getting the best sleep you can, Foster recommends limiting light sources late at night – do you really need to brush your teeth under a spotlight? – and getting out in the sunlight early in the morning to keep your body clock online. Powles recommends making the most of the daylight hours, spending time outdoors and staying active – to strengthen your immune system and help you de-stress. All the other usual advice still applies, of course – no phones in the bedroom, don’t drink a pint of coffee at 6pm – but, realistically, if your only problem is tiredness, just try going to bed a bit earlier.