What Is Insomnia? Causes of Sleeplessness, Sleep Habits and When to Seek Medical Advice

Many people have experienced sleep problems such as struggling to fall asleep after getting into bed, waking several times during the night, or waking too early and being unable to get back to sleep.

Temporary difficulty sleeping can happen to anyone, particularly during busy periods or when dealing with strong stress related to work, relationships or other life circumstances.

However, when difficulty sleeping continues and causes daytime sleepiness, fatigue, difficulty concentrating or other problems that affect everyday life, it may need to be considered differently from occasional sleep loss.

When researching insomnia, you may also come across statements such as:

“I can’t sleep because my autonomic nervous system is out of balance.”
“This nutrient will help me sleep.”
“I just need to make my parasympathetic nervous system dominant.”

However, there is no single cause of sleep difficulty.

Sleep problems may be associated with many different factors, including daily routines, stress, light exposure, caffeine, alcohol, the bedroom environment, pain, itching, medications, changes associated with menopause, sleep disorders such as sleep apnoea, and other physical or mental health conditions.

This article explains what insomnia is, how it differs from simply having trouble sleeping, common patterns of sleep difficulty, factors that may affect sleep, the relationship between the body clock and light, everyday sleep habits, and when it may be appropriate to seek medical advice.

What is insomnia? Difficulty sleeping and insomnia disorder are not the same

Having one night when you struggle to fall asleep does not automatically mean that you have insomnia disorder.

For example, temporary difficulty sleeping may occur when:

• You feel nervous about an important event the following day
• You are thinking about work or family concerns
• Your sleeping environment has changed because of travel or moving house
• You have taken a long daytime nap
• You are trying to sleep at a different time from usual

Temporary sleep difficulties like these are experienced by many people.

Insomnia involves more than what happens during the night

Insomnia is not determined simply by the number of hours you sleep.

Even when there is adequate opportunity to sleep, a person may experience:

• Difficulty falling asleep
• Repeated waking during the night
• Waking too early and being unable to return to sleep
• Sleeping but not feeling adequately rested

When these problems continue, it is also important to consider whether they are associated with daytime difficulties such as:

• Significant daytime fatigue
• Difficulty concentrating
• Problems carrying out work or household tasks
• Low or unsettled mood
• Difficulty functioning normally during the day

For chronic insomnia disorder, diagnostic criteria also include sleep difficulties and related daytime symptoms occurring at least three times per week for at least three months.

However, an actual diagnosis is made by a doctor who considers the symptoms, circumstances and other relevant factors as a whole.

In other words, having nights when you cannot sleep is not the same as having insomnia disorder.

The amount of sleep people need varies

Some people may believe that everyone needs exactly eight hours of sleep every night in order to be healthy.

However, sleep needs vary between individuals and also change with age.

For this reason, sleep duration alone cannot tell you whether there is a problem.

For example:

“I only slept six hours, so I must have insomnia.”
“I slept eight hours, so everything must be fine.”

Neither conclusion can be made from sleep duration alone.

It is also important to consider factors such as how rested you feel when you wake, daytime sleepiness and whether sleep is affecting everyday life.

What different forms can insomnia take?

Not everyone who experiences insomnia has the same type of sleep difficulty.

Sleep problems may appear in several different ways.

Difficulty falling asleep

This refers to taking a long time to fall asleep after getting into bed.

Sometimes, the more strongly a person thinks, “I have to sleep,” the more anxious or tense they become, which may make falling asleep feel even more difficult.

However, the amount of time it takes to fall asleep naturally varies between individuals.

One night of difficulty falling asleep does not mean that you have insomnia disorder.

Waking during the night

This refers to waking repeatedly after initially falling asleep.

Waking during the night can become more common with age, but other factors may also interrupt sleep, including:

• Needing to urinate frequently
• Pain or itching
• Feeling too hot or too cold
• Loud snoring or breathing problems
• The effects of alcohol

Waking too early

This refers to waking considerably earlier than intended and being unable to fall asleep again.

Sleep timing can naturally shift earlier with age, so waking early does not by itself indicate a medical problem.

However, when early waking persists and also affects daytime life, it may be worth assessing overall sleep patterns.

Sleeping but not feeling rested

Some people may get what appears to be an adequate amount of sleep but still feel:

“I don’t feel like I slept deeply.”
“I still feel tired when I wake up.”

This may sometimes be described as difficulty obtaining restorative sleep or reduced sleep-related restfulness. Sleep duration alone does not provide the full picture, and factors such as continuity of sleep, medical conditions, the sleep environment and the person’s own sense of restoration should also be considered.

In particular, if you are sleeping for an apparently adequate amount of time but continue to experience severe daytime sleepiness, another sleep disorder may be involved rather than insomnia alone.

Why can’t I sleep? Common factors associated with insomnia

There is no single explanation for why someone may have difficulty sleeping.

Even when two people both struggle to fall asleep, the underlying factors may be very different.

Stress and persistent thoughts

Psychological stress related to work, relationships, family issues or worries about the future can sometimes make it harder to sleep.

It is also common to sleep poorly the night before an event that makes you feel nervous or tense.

However, the presence of stress does not mean that every case of insomnia can simply be explained as an “autonomic nervous system imbalance”.

If sleep problems continue, other possible contributing factors should also be considered.

Changes in daily routine

Large changes in waking and sleeping times can cause a mismatch between the time you try to sleep and your body's natural sleep–wake rhythm.

Examples include:

• Sleeping until around midday on weekends
• Regularly staying up very late
• Taking long daytime naps
• Working night shifts or rotating shifts
• Travelling across time zones

These situations may change the timing of sleep.

Caffeine

Coffee, green tea, black tea and energy drinks can all contain caffeine.

Because caffeine has a stimulating effect, the amount consumed and the time of day it is consumed may affect the ability to fall asleep.

People vary considerably in their sensitivity to caffeine, so there is no need to apply one strict cut-off time to everyone. However, if you are having difficulty sleeping, reviewing caffeine intake from the afternoon into the evening may be useful.

Alcohol

Alcohol can make people feel sleepy, which is why some people use it as a nightcap.

However, although alcohol may initially make it seem easier to fall asleep, it can make sleep lighter later in the night and may increase nighttime awakenings.

For this reason, it is best not to make “drinking because I can’t sleep” a regular sleep strategy.

Smoking and nicotine

Nicotine has stimulating effects, so smoking may also affect sleep.

If smoking shortly before bed has become a habit, it may be worth considering whether it is contributing to sleep difficulties.

The bedroom environment

Sleep can also be disturbed if the bedroom is:

• Too bright
• Too hot or too cold
• Noisy
• Uncomfortable because of unsuitable bedding

The ideal temperature and bedding differ between individuals, but creating a quiet, comfortable environment where you can rest is an important part of healthy sleep.

Pain, itching and other nighttime symptoms

Back pain, joint pain, itchy skin, coughing, nasal congestion or frequent urination can also interrupt sleep.

In these situations, rather than focusing only on sleep itself, it is important to seek appropriate assessment and treatment for the symptom that is disturbing your sleep.

Medical conditions and medications may also be involved

Persistent sleep problems may sometimes be associated with:

• Sleep apnoea
• Restless legs syndrome
• Mental health conditions such as depression
• Respiratory or cardiovascular conditions
• Thyroid disorders
• Symptoms associated with menopause
• The effects of medications

For this reason, persistent insomnia should not simply be self-diagnosed as being caused by “stress” or “the autonomic nervous system”.

The body clock, light, melatonin and sleep

Our sleep and wakefulness are strongly influenced by the body clock, or circadian rhythm.

The body clock helps regulate the timing of sleep and wakefulness, body temperature, hormone secretion and other processes across an approximately 24-hour cycle.

Light during the morning and daytime helps regulate the body clock

Light is one of the most important signals that helps synchronise the body clock with the external day–night cycle.

Exposure to light during the morning and daytime helps regulate the sleep–wake rhythm.

By contrast, prolonged exposure to bright light at night may delay the body's recognition that it is nighttime.

Melatonin is a hormone involved in the sleep–wake rhythm

When reading about sleep, you may often come across the term melatonin.

Melatonin is a hormone produced by the pineal gland in the brain. Its secretion is suppressed during brighter periods and generally increases as the environment becomes darker at night.

Together with the body clock, these changes help create physiological conditions that support sleep at night.

However, the process is not as simple as saying:

“Morning sunlight will always make you sleepy exactly a certain number of hours later.”
“Increasing melatonin will cure insomnia.”

Sleep is influenced not only by the body clock but also by physical activity, prior sleep loss, age, environment, health and many other factors.

Do not think about nighttime smartphone use in terms of “blue light” alone

You may have heard that blue light from smartphones causes insomnia.

Looking at bright smartphone or tablet screens at night may affect sleep, but blue light is not the only consideration.

Other factors may include:

• Exposure to bright screens
• Watching social media or videos for so long that bedtime becomes later
• Checking work emails and remaining mentally engaged
• Using a smartphone for long periods while in bed

These behaviours may also interfere with sleep.

If you are having difficulty falling asleep, it may therefore be helpful to review how you use smartphones and tablets before bedtime rather than focusing only on blue light.

Menopause and changes in sleep

During menopause, some women notice that it becomes more difficult to fall asleep or that they wake more often during the night.

As ovarian function declines during menopause, levels of oestrogen fluctuate considerably and gradually decrease.

However, changes in sleep during menopause cannot simply be explained as “lower oestrogen causes insomnia”.

Hot flushes and sweating may interrupt sleep

Menopause may be associated with symptoms such as:

• Hot flushes
• Feeling overheated
• Sweating
• Palpitations

If these symptoms occur at night, they may make it harder to fall asleep or may cause a person to wake during sleep.

Heavy night sweats may also make clothing or bedding uncomfortable and interrupt sleep.

Mood and life circumstances may also affect sleep

Menopause often occurs during a stage of life when work, family responsibilities, relationships, caring for ageing parents or children becoming independent may create major changes in everyday life.

Anxiety, irritability and low mood may also affect sleep.

For this reason, sleep problems during menopause may involve several interacting factors, including:

• Changes in female hormones
• Physical symptoms such as hot flushes and sweating
• Psychological stress
• Life circumstances
• Age-related changes in sleep

Do not assume that every sleep problem in your 40s or 50s is menopause

When sleep problems occur during the 40s or 50s, it can be easy to assume that they are simply part of menopause.

However, other possible causes may include:

• Sleep apnoea
• Restless legs syndrome
• Thyroid disorders
• Pain or frequent urination
• Mental health difficulties
• Medication effects

If persistent insomnia occurs alongside symptoms that may be related to menopause, consider discussing them with a gynaecologist, GP or other appropriate healthcare professional.

Everyday habits to consider for healthy sleep

When you cannot sleep, it is understandable to look for one technique that will help you sleep well that very night.

However, sleep is not determined by a single rule such as:

“Eating this food will make me sleep.”
“Sleeping at this exact time will always improve sleep quality.”
“Making the parasympathetic nervous system dominant will make me sleep.”

Instead, it is helpful to consider your overall daily routine, including waking time, light exposure, activity, diet, caffeine, alcohol and the bedroom environment.

Avoid large changes in your waking time

After a poor night’s sleep, it can be tempting to try to catch up by sleeping until around midday.

However, repeatedly waking much later than usual may also shift the time when you naturally become sleepy that evening.

Your waking time does not need to be identical every day, but avoiding very large changes can help maintain a more consistent sleep–wake rhythm.

Get appropriate light during the morning and daytime

Morning and daytime light provide an important signal that helps synchronise the body clock with the external day.

Simple habits such as opening the curtains after waking or spending some time outdoors during the day can help you receive natural light as part of everyday life.

At night, avoiding unnecessarily bright lighting for long periods may also help create an environment more suited to sleep.

Review smartphone use before bed

As discussed above, nighttime smartphone use is not only about light. Long periods of use may also delay bedtime.

If you are having difficulty falling asleep, try reducing screen time immediately before bed and allow yourself some time to transition into preparing for sleep.

Stay physically active during the day

Exercise and general physical activity are also important parts of healthy sleep habits.

You do not necessarily need intense exercise.

• Walk more often
• Do gentle stretching
• Reduce prolonged periods of sitting
• Choose physical activity appropriate for your fitness level

The most useful approach is one that you can continue without excessive strain.

Avoid very long or late naps

After insufficient sleep, it is normal to feel sleepy during the day.

A short nap may sometimes be helpful, but sleeping for a long period or napping late into the afternoon or evening may make it harder to fall asleep that night.

If nighttime sleep difficulties are continuing, consider reviewing both the timing and duration of your naps.

Pay attention to when you consume caffeine

People vary in how strongly caffeine affects them.

Caffeine is found not only in coffee but also in drinks such as:

• Green tea
• Black tea
• Energy drinks
• Some soft drinks

If you are struggling to fall asleep, consider how much caffeine you consume during the day and when you usually consume it.

Do not use alcohol as a sleep strategy

Alcohol can make you feel sleepy, but sleep may become lighter later in the night and you may wake more frequently.

Using alcohol regularly to help with sleep can also lead some people to gradually increase the amount they drink.

For this reason, avoid making “drinking because I cannot sleep” a regular habit.

Do not rely on a particular “sleep food”

When researching sleep, you may encounter information about nutrients such as tryptophan, vitamins and minerals.

These nutrients are, of course, important for maintaining general health.

However, eating one particular food or nutrient does not by itself treat insomnia.

Rather than consuming large amounts of one particular food, aim for an overall balanced diet that includes staple foods, protein-containing foods, vegetables and fruit.

Eating a large meal immediately before going to bed may also contribute to discomfort or difficulty sleeping in some people.

Try not to put too much pressure on yourself to sleep

When insomnia continues, thoughts such as:

“I absolutely have to sleep for eight hours tonight.”
“I have to fall asleep early or tomorrow will be terrible.”

can easily increase anxiety.

Spending a long time in bed repeatedly thinking that you “must sleep” may increase tension and make sleep feel even more difficult.

Rather than going to bed very early when you are not sleepy, another approach is to wait until you begin to feel sleepy before getting into bed.

When persistent sleep problems should be medically assessed

If sleep problems continue despite reviewing your daily routine and sleep environment, and they begin to affect your daytime life, consider seeking medical advice.

Sleep difficulties can sometimes be associated not only with insomnia disorder but also with other sleep disorders and physical or mental health conditions.

Daytime functioning is being affected

Consider seeking advice if problems such as the following continue:

• Severe sleepiness makes it difficult to concentrate at work or while studying
• Fatigue significantly affects daily life
• You are making more mistakes at work or while doing household tasks
• Low mood or anxiety continues
• You are becoming extremely anxious about not being able to sleep

You have been told that you snore loudly or stop breathing during sleep

Some breathing problems during sleep can occur even when a person does not personally feel that they are sleeping poorly.

Signs that may warrant assessment include:

• Loud snoring
• Someone noticing that you stop breathing during sleep
• Repeated nighttime awakenings
• Headaches on waking
• Severe daytime sleepiness despite apparently adequate sleep

These symptoms may warrant assessment for conditions such as sleep apnoea.

Uncomfortable sensations in your legs prevent sleep

If your legs feel unpleasant or restless at night and you feel a strong urge to move them while sitting or lying still, restless legs syndrome may be one possible explanation.

If the problem persists, rather than simply tolerating it as “difficulty falling asleep”, consider discussing the symptoms with a healthcare professional.

Pain, itching or frequent urination repeatedly wakes you

Sometimes the main problem is not sleep itself but symptoms such as:

• Pain
• Itching
• Coughing
• Nasal congestion
• Frequent nighttime urination

If these symptoms repeatedly interrupt sleep, addressing their underlying cause is important.

Rather than focusing only on “fixing sleep”, discuss the symptoms that are disturbing your sleep with an appropriate healthcare professional.

You are experiencing persistent low mood or anxiety

Insomnia can sometimes occur alongside mental health difficulties.

If severe low mood, anxiety or loss of motivation continues, it is important not to treat the problem as sleep alone and to seek appropriate professional advice.

Do not become excessively afraid of sleeping medication

Some people worry that “once you start sleeping medication, you will never be able to stop” or that “all sleeping medication causes dependence”.

There are many different types of sleep medications, and their effects and precautions vary.

Doctors consider factors such as symptoms, age, other medical conditions and medications before deciding which treatment may be appropriate.

Some medications can cause side effects such as sleepiness or dizziness, and certain medicines require particular care with longer-term use. However, it is not appropriate to assume that sleeping medications are dangerous while supplements are automatically safer.

If you have been prescribed sleep medication, do not suddenly stop taking it or change the dose on your own. Discuss any concerns with your doctor or pharmacist.

Summary: do not assume there is only one cause of sleeplessness

Everyone has nights when sleep is difficult.

One night of struggling to fall asleep does not automatically mean that you have insomnia disorder.

However, when problems such as:

• Difficulty falling asleep
• Repeated waking during the night
• Waking too early
• Sleeping without feeling adequately rested

continue and begin to affect daytime life, it may be worth looking more closely at your sleep.

Important points to remember include:

• Difficulty sleeping and insomnia disorder are not the same thing
• Sleep needs vary between individuals
• Insomnia is not caused only by stress or the autonomic nervous system
• Light exposure and daily routines influence the sleep–wake rhythm
• Caffeine and alcohol may affect sleep
• Do not try to treat insomnia with one particular food or supplement
• Several factors may contribute to sleep changes during menopause
• Persistent symptoms should be appropriately assessed

When sleep is difficult, it is easy to become anxious about having to sleep or to try one health remedy after another.

Instead, start by reviewing everyday factors such as waking time, light exposure, physical activity, diet, caffeine, alcohol and the bedroom environment.

If you continue to have difficulty sleeping despite having adequate opportunity for sleep, or if your daytime life is being significantly affected, avoid relying only on self-diagnosis and consider seeking medical advice.