When you're feeling exhausted, the first advice is always to get more sleep.
It makes sense that you're nodding off in the afternoons if long work hours or a screaming toddler are interfering with your rest.
But some of us spend our days tired and lethargic even after getting the recommended 7+ hours of shut-eye every night. So, what's going on?
As this episode of AsapSCIENCE explains, there's a wide range of reasons you could be constantly fatigued even if you think you're getting enough sleep:
width="700″ height="414″ seamless="seamless" allowfullscreen="allowfullscreen">
For starters, you might just be too sedentary.
Even though we think of physical exertion as exhausting, it turns out that doing light exercise just a few times a week can leave you more energised.
Just think back to a time when you've had an unusually active day outdoors, maybe going on a hike or throwing frisbee in the park.
Chances are you slept exceptionally well that night. People who exercise regularly get to enjoy a better night's sleep, even if the number of hours they sleep remains the same.
Another common trap is our reliance on caffeine to stay awake.
Even though most of us wouldn't guzzle espresso straight before bed, the window for avoiding caffeine is actually much longer.
Caffeine blocks adenosine, a neurotransmitter that accumulates in the brain throughout the day, making us drowsy in the evenings.
If you have coffee even as early as six hours before bed, it will mess with your adenosine production, making it harder to go to sleep.
Besides, studies have shown that caffeine actually messes with our circadian rhythms.
But sometimes your exhaustion is not down to simple lifestyle choices, and instead is related to mental health, the video above explains.
For example, generalised anxiety disorder can come with fatigue, and even just high levels of stress and worrying will leave you pretty drained.
Depression comes with an impact on quality of sleep as well, even causing insomnia in some cases.
Apart from mental health, physical conditions can also cause excessive tiredness. Those are best left to be diagnosed by your doctor, but include such things as iron deficiency, thyroid problems and diabetes.
So, there's really no one quick solution for dealing with constant fatigue, but at least AsapSCIENCE gives you a handy checklist of things to look out for.
A lot of their advice - like the tip about exercise - is pretty easy to take on board, unless you are dealing with 'social jetlag', which we'll let the video explain in detail.
Maybe you're just one of those people not built for a 9-5 lifestyle, in which case we're sorry.
Here, have a coffee nap.
A version of this article was first published in April 2017.
A bad night's sleep can leave you feeling pretty tired the next day. Put a string of those together and nagging fatigue starts to set in.
Getting good sleep, in the right amount, can make a big difference in how you feel. Too little or too much sleep can increase your perception of fatigue. And even if you get enough hours of sleep, you might find yourself dragging the next day if that sleep was interrupted by frequent awakenings or was of poor quality.
Although most of us need about eight hours a night to feel refreshed during the day, what counts as sufficient sleep is highly individual. It makes sense that getting less sleep than you need might leave you feeling tired, but you may be surprised to learn that getting more sleep than you need may not leave you refreshed and energized. In fact, many people find that on days when they hit the snooze button more times than usual, they feel more lethargic and unmotivated.
Research bears out the connection between too much sleep and too little energy. It appears that any significant deviation from normal sleep patterns can upset the body's rhythms and increase daytime fatigue. The best solution is to figure out how many hours of sleep are right for you and then stick with it — even on weekends, vacations, and holidays.
For more information on the role of sleep in feeling energized, read Boosting Your Energy, a Special Health Report from Harvard Medical School.
Image: © Mladen Zivkovic/Getty Images
As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles.
No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.