It seems simple. When you feel tired, you need to sleep. However, other signs that you need to get more rest may be less clear. Besides feeling tired or drowsy or seeing dark circles under your eyes, you might notice subtle signs like skin breakouts, achy muscles, or vision changes.

Sleep is vital to life, like eating, drinking, and breathing. These 15 cues mean you may need to give yourself a break and take a rest.

1. Dark Circles

The skin around your eyes is the thinnest and most fragile on your body. If you are not getting enough sleep, your skin cells don’t repair themselves as efficiently, and it shows under your eyes. You see the damage as dark circles, which happen as blood pools under your eyes from lack of circulation.

If the skin around your eyes looks slack or pale, it may be due to poor sleep quality, which can weaken the skin barrier and lead to signs of aging like wrinkles or fine lines around the eyes, known as crow’s feet.

2. Fatigue

Being tired at the end of the day or drowsy at bedtime is not the same thing as fatigue, which is more severe than simply feeling tired. If you feel weak or lack energy and find you have trouble keeping going during the day, your body could be telling you that you need to find a way to get more rest regularly.

3. Muscle Aches

If you have mysterious aches and pains, it could be that you’re lacking sleep. Your body repairs and builds tissues while you sleep. Insufficient rest can also lead to inflammation, which is strongly connected to pain.

Not getting enough rest can make you more sensitive to pain, as well, and it increases the risk of developing chronic pain.

4. Trouble Sleeping

When you were a kid, you might have been told you were “overtired” when you were up past your bedtime. That’s a real thing, and it can happen when you have been super active, either through intense physical exercise (like overtraining) or a tough mental workout. Stress can do it, too. Your body can’t wind down and let you sleep, no matter how exhausted you are, if you are overstimulated.

5. Poor Daytime Performance

If you’re feeling less productive during the day, it could be due to a lack of sleep. You may take longer to do familiar tasks, you make more mistakes, your reaction time is slowed.

Losing just one to two hours of sleep a night over several nights can affect your ability to function just as much as if you pulled an all-nighter. Actions like driving can be more hazardous, and you may act more impulsively. Cognitive functions like learning, memory, and attention are not as sharp.

Motor skills can also be affected. A study showed that tired students could not keep up with the beat of a metronome when walking, compared to students who were getting more sleep.

6. Low Motivation

Sleep deprivation can affect brain circuitry involved in how much you value the amount of effort you make. If you’re sleep-deprived, an extra push may not feel worth it. You may not want to put in the work to get the potential rewards from your accomplishments. If you’re feeling unmotivated, try getting more rest.

7. Vision Changes

When you sleep, your body and brain are in recovery mode, including your eyes and vision. If you have dry, itchy, or bloodshot eyes, it could be that you are producing fewer tears because you’re not sleeping enough.

Your eyesight may be blurred because your eyes are too tired to make rapid adjustments. Eye twitches can be another sign of too-tired eyes, which may feel more sensitive to light.

8. Memory Lapses

Your brain needs rest to file away all that’s happened each day for future reference. It organizes neural connections for you while you sleep, and your memory may suffer if you’re not getting enough rest.

Lack of sleep can also lead to microsleep, which is when you fall asleep for a few seconds and don’t even notice it. If you’re in a class or at a work function, you might miss some important information because you had a “micro nap,” so get rest to stay sharp.

9. Weight Gain

Sleep deprivation can cause you to confuse tiredness with hunger. Your body is trying to find the energy it needs to get a good night’s sleep, so you may make poorer food choices when tired.

Sleep is also important to balance hormones that are connected to hunger. If you are not getting enough sleep, you may produce more of the hormone ghrelin, which can make you want to eat. If you’re rested, you may have more leptin, which is associated with feeling full.

10. Moodiness and Feeling Irritated

Sleep and mood are closely related. If you’re tired, you are more likely to become irritated. Tired people often respond more strongly to stressful situations and have fewer positive reactions to daily experiences. Poor sleep can make it much more difficult to deal with the stress of daily life and can even distort how you see the world.

11. Increased Anxiety and Depression

If you have chronic insomnia and are not sleeping well for at least three nights a week for three months or longer, your risk of developing anxiety or a mood disorder like depression increases.

Anxiety and mood disorders can also cause insomnia, creating a vicious cycle. If you are experiencing anxiety or feel withdrawn or sad, consider how well you’ve been sleeping.

12. Sex Drive

If you don’t feel inclined toward intimacy, it could be due to a lack of sleep. Sleep deprivation can have a complicated effect on your libido—the desire for sex. Some of it is psychological, and some is physiological.

Not getting enough sleep lowers testosterone levels, the hormone that can reduce sex drive in people of any sex. On the other hand, there is some early evidence that less sleep may increase the desire for sex, though not sexual activity. It may also lead to greater dissatisfaction with sexual activity in women.

Women who get enough sleep may notice an increase in both the desire for sex and physical arousal. One study found that women who increased their sleep by one hour had a 14% increase in sexual activity the next day.

13. Increased Resting Heart Rate

If you feel your heart is pounding, or if you measure your heart rate regularly and notice it’s been going up, think about how much you’re sleeping. Resting heart rate (RHR) is how often your heart beats per minute when you are calmly sitting or lying down.

When you’re not sleeping enough, the levels of the hormone cortisol can go up, which can increase your heart rate. In athletes, a higher than usual resting heart rate is a sign you have not fully recovered from physical activities and may be overtraining. Psychological disorders that can develop from lack of sleep, like chronic anxiety, can also make your heart beat faster.

14. Skin Blemishes and Other Changes

If you notice your skin isn’t looking so good, consider how much you’ve been sleeping. When you sleep, the blood flow to your skin increases, which helps repair and prevent skin damage. If you lack sleep, it can disrupt the skin barrier and affect beneficial bacteria like Staphylococcus epidermis that live on your skin and help protect it from drying out.

Lack of sleep can lower the production of collagen and elastin (among other proteins) that keep your skin looking plump and healthy. If your cortisol levels are up because you’re not sleeping enough, the rapid heartbeat that can result has been shown to worsen acne.

15. Getting Sick More Often

If you are catching colds or other infectious diseases more than you used to, lack of sleep could contribute to it. Your immune system needs sleep to function well. When you’re tired, you don’t make as many antibodies and other immune system proteins, which fight infection.

One older study found that people who typically get less than seven hours of sleep are almost 3 times more likely to catch a cold.

Over time, sleep deprivation can raise the risk of developing serious health problems, including heart disease, high blood pressure, obesity, and stroke.

Summary

Sleep is vital to good health, and if you don’t get enough of it, both your physical and psychological health can suffer. There are many signs that you’re not getting enough sleep besides feeling simply tired. Understanding them can make you more aware of sleep deprivation, so you can take steps to get the rest you need.