Why can't I sleep? 12 common causes and what to do

Around one in five adults experience insomnia or significant sleep problems at any given time.¹ But the good news is that for the vast majority of people, not being able to sleep is temporary.

Here are some of the most common reasons why you can't sleep and what you can do about it.

Reasons why you can't sleep

1. Stress and anxiety

Stress and anxiety are among the most common causes of sleep problems. People with anxiety are more likely to experience insomnia as worrying about work, finances, family, or other concerns can keep the mind active when it's time to sleep.²

This can lead to overthinking, restlessness, and frequent waking during the night.

2. Too much caffeine

Caffeine is a stimulant that can remain in your body for several hours. Coffee, tea, energy drinks, and some fizzy drinks may make it harder to fall asleep, particularly if consumed later in the day.

Studies have shown that caffeine consumed even six hours before bedtime can disrupt sleep and reduce total sleep time.³

Reducing caffeine intake in the afternoon and evening may improve sleep quality.

3. Screen time before bed

Phones, tablets, and televisions emit blue light, which can interfere with the production of melatonin, the hormone that helps regulate sleep.⁴

Scrolling social media or watching stimulating content may also keep your brain alert when it should be winding down.

4. Depression and low mood

Sleep problems and depression often go hand in hand. Some people with depression struggle to fall asleep, while others wake up very early and cannot get back to sleep.⁵

Persistent low mood, loss of interest in activities, and tiredness during the day may suggest depression is contributing to your sleep difficulties.

5. Pain and discomfort

Chronic pain, arthritis, headaches, back pain, and other physical conditions can make getting comfortable difficult. Pain may also cause you to wake during the night.⁶

Treating the underlying cause of discomfort can often help improve sleep.

6. Medication side effects

Certain medications can affect sleep.⁷ These include:

• Some antidepressants.

• Steroids.

• Asthma medications.

• Decongestants.

• Blood pressure medicines.

If you think a medication is affecting your sleep, speak to your doctor or pharmacist before stopping treatment.

7. Sleep apnoea

Sleep apnoea is a condition that causes breathing to repeatedly stop and start during sleep. This can disrupt your sleep and prevent you from getting enough restorative rest.⁸

As a result, people with sleep apnoea may wake up frequently throughout the night, even if they do not remember doing so.

If you think you or someone you know has sleep apnoea, you should see your doctor for a medical assessment and treatment.

8. Restless leg syndrome

Restless leg syndrome causes uncomfortable sensations in the legs and an overwhelming urge to move them, especially in the evening or at night.

Symptoms often become worse when lying down and can make it difficult to fall asleep.⁹

9. Menopause

Hormonal changes during perimenopause and menopause can disrupt the body's sleep-wake cycle, making it harder to get a good night's sleep.¹⁰

Symptoms such as hot flushes, night sweats, and anxiety may make it difficult to fall asleep or cause frequent waking during the night.

As a result, sleep disturbances and insomnia are common during perimenopause and menopause.

10. Alcohol and nicotine

Although alcohol may make you feel sleepy initially, it can disrupt sleep later in the night and increase the likelihood of waking up.¹¹ Nicotine, meanwhile, is a stimulant that can make it harder to fall asleep and stay asleep.¹²

As a result, both alcohol and nicotine can reduce sleep quality and contribute to insomnia symptoms. Reducing alcohol and quitting smoking may help improve sleep quality.

11. Pregnancy

Hormonal changes, physical discomfort, frequent peeing, and anxiety about the upcoming birth can all contribute to insomnia during pregnancy.¹³

Sleep difficulties are particularly common during the first and third trimesters.

12. Irregular sleeping patterns

Shift work, jet lag, and inconsistent bedtimes can disrupt your body's natural sleep-wake cycle, making it harder to fall asleep and wake up at the times you want.¹⁴

This can lead to difficulty falling asleep, frequent waking, and poor-quality sleep. Going to bed and waking up at similar times each day may help restore a healthy routine.

Why am I tired but can't sleep?

Feeling exhausted but unable to sleep is common. Stress hormones such as cortisol can keep your brain alert even when your body feels tired.

Anxiety, caffeine, irregular sleep patterns, and some medical conditions can all contribute to this feeling.

Why do I wake up at 3 am?

Waking up in the middle of the night occasionally is normal. However, regularly waking at 3 am may be linked to:

• Stress or anxiety.

• Alcohol consumption.

• Hormonal changes.

• Blood sugar fluctuations.

• Sleep apnoea.

• Environmental disturbances such as noise or room temperature.

If you wake up at 3 am regularly, try not to watch the clock or use your phone, as this can make it harder to fall back asleep.

What to do if you can't sleep

If you cannot sleep, experts recommend:

While these techniques can help when you can't sleep, building a consistent sleep routine and learning how to fall asleep more effectively may help prevent future sleep problems.

How to fall asleep faster

The following strategies may help you fall asleep faster and improve overall sleep quality.

Many people find that improving their sleep habits consistently over several weeks makes a noticeable difference.

When to see a doctor

Speak to a doctor if:

• Sleep problems last longer than several weeks.

• Insomnia affects your work or daily life.

• You feel excessively tired during the day.

• You snore heavily or stop breathing during sleep.

• Pain, anxiety or low mood are contributing to poor sleep.

• Home remedies are not helping.

Persistent insomnia may require further assessment to identify an underlying cause.

Summary

There are many reasons why you may struggle to sleep, ranging from stress and caffeine to medical conditions such as sleep apnoea and restless leg syndrome.

Making small lifestyle changes can often improve sleep, but persistent or severe insomnia should be assessed by a healthcare professional. Identifying the underlying cause is the first step towards getting better quality sleep and feeling more rested.