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What Causes Sleep Issues and Insomnia? - The Complete Guide

by Dale Cudmore | Updated: Apr 23, 2021

While the concept of sleep is simple, there are a lot of complex interactions that can affect sleep quality.

This guide contains an exhaustive list of potential causes of sleep issues.

Just a single one of these causes can lead to any one of the different types of insomnia, and having multiple risk factors can increase the severity.

Gender (Sex) Can Cause Sleep Issues

Hormone levels can affect sleep quality, which is more of an issue for biologic women than men.

However, there are lifestyle factors based on cultural norms that can also play a role.

We’ll look at both types of causes.

Male Sleep Issue Causes

Men are in general less likely to develop insomnia due to smaller fluctuations in hormone levels, but still easily can.

See our guide to causes of insomnia in males for complete details, but the most common gender-specific issues are:

  • Obesity - While obesity comes with an increased risk of insomnia for all people, men are more likely to be obese.
  • Prostate cancer - Research shows that the treatments for prostate cancer are associated with increased risk of insomnia (1).
  • Caffeine consumption - In Western countries at least, men have a higher level of caffeine consumption (We’ll look at caffeine in more detail soon). This is not only from drinks like coffee, but men drink far more energy drinks on average (2).
  • Arousal - While it varies heavily among individuals, men (particularly younger ones) are known for having higher sex drives, which can make it more difficult to get to sleep.

Female Sleep Issue Causes

A lot of insomnia research focuses on women because they have significantly higher rates of insomnia.

The most common female-specific causes are related to:

  • Depression - It’s a complex topic that we don’t have all the answers to, but women appear to have a much higher rate of depression (3). Depression and insomnia are heavily interlinked (more on that later).
  • Menstruation - Research shows that women suffer lower sleep quality during periods (4). Also note that while it's not common, birth control can cause insomnia for some individuals.

Diet and Nutrition

It’s not really a surprise that what you eat and drink can affect your sleep quality.

Different Types of Diets can Cause Sleep Issues

Many types of diets can be healthy, but when you switch suddenly to a new one, it takes your body some time to adjust. In this time, sleep issues are a common side effect.

Additionally, some diets can lack certain nutrients if not planned correctly (e.g. vegan diets are often low in iron) that are important for sleep.

The most popular diets that have anecdotal reports of sleep problems are:

  • Keto - The ketogenic diet (low carbohydrates, high fat) has become very popular. But carbohydrates really help some people sleep, so it can take quite some time to adjust for certain people (if they can at all), which is why ketogenic diets can cause insomnia.
  • Vegan - As mentioned, vegan diets can lack certain nutrients. They also tend to be lower in fats, and some fats are critical to hormone production and function, which can affect sleep. Here’s a guide to vegan insomnia if you’re looking for more.
  • Intermittent fasting - Many people report insomnia while adjusting to intermittent fasting, but there are no other reasons for it to cause insomnia after getting used to it (other than maybe eating too much just before bed).
  • Gluten-free - Some people say they sleep better on a gluten-free diet, while others have issues caused by the substitutes used in place of gluten. Not much research has been done on this diet in regards to sleep troubles. See our post on gluten-free diets and insomnia for more details.
  • Whole 30 - Not very different from vegan diets in most cases, and it comes with the same risks.

Loss of appetite and insomnia can also be a sign of a greater underlying condition that should be seen by a doctor.

One final thing to mention is that large calorie deficits, particularly for sustained time periods, can affect hormone production and sleep quality as a result.

Certain Foods Are Known to Affect Sleep Quality

On top of your general diet, specific foods can cause sleep trouble for certain people.

Most foods won’t have that much of an effect. For example some people say that garlic or ginger cause insomnia, others say they make it better. Either way, it will be a small difference if you eat those foods in reasonable quantities.

However, there are a few foods that are different:

  • Coffee, energy drinks, and other caffeine sources - It’s pretty obvious to most that caffeine consumption affects sleep, which numerous studies confirm (7,8). While the amount of caffeine ingested matters, as a whole, caffeine consumers are about 1.4 times to develop insomnia than the general population. See how caffeine causes insomnia for more specific detail.
  • Sugar - The effect of sugar consumption on sleep has been studied fairly extensively in school children. Multiple studies have suggested that consuming a large amount of refined sugar can cause sleep issues and even insomnia (9,10).
  • Chocolate - Most people don't know that chocolate can cause insomnia symptoms, mainly due to containing caffeine and sugar.

There are also some controversial foods and drinks like green tea. Green tea can contribute to insomnia in some, and improve sleep in others. It usually comes down to the caffeine content of the tea, as well as when it is consumed.

Nutritional Supplements

Too many people hold the misconception that taking tons of vitamin supplements is what healthy people do.

But just as lacking a nutrient is harmful, having too much of certain ones can also cause health issues, including sleep problems.

For now we don’t have guides to every single supplement out there, but here are a few:

  • Can zinc cause insomnia? - For most people, zinc improves sleep quality, but there are some that it doesn’t.
  • Can too much Vitamin D cause insomnia? - It’s pretty hard to get too much vitamin D from the sun, but too much vitamin D from supplements can cause sleep trouble.
  • Can magnesium glycinate cause insomnia? - For those with a magnesium deficiency, a supplement typically improves sleep quality. However, some people get too much magnesium or have a reaction to this particular type of magnesium.
  • Does CoQ10 cause insomnia? - Research suggests that CoQ10 supplementation may improve aging, heart health, fertility, and more. However, some patients do report it causing sleep problems.

One other factor to consider is that supplements and medications can have unexpected interactions with each other, causing sleep issues and other serious health problems.

That’s why even for something that seems simple like a vitamin D supplement, it’s recommended to consult a doctor before taking it.

Substance Use

This is a short section because everyone knows that drugs of almost any kind will have some effect on behavior, and that includes sleep in most cases.

Insomnia is most prevalent in drinkers that have 3 or more alcoholic drinks per day. Even if you quit drinking, insomnia usually lasts 3-6 months after.

Harder drugs are going to have even more significant effects, but not surprisingly they have not been studied in depth (can’t exactly go around giving people illegal drugs).

Stress, Anxiety, and Overthinking

When it comes to mental health, stress levels are arguably the most important factor.

Research shows that most acute (temporary) insomnia is caused by stressful events (11). This can lead to recurring insomnia through sleep anxiety.

People that are fairly stressed or anxious all the time are much more likely to develop chronic insomnia and other conditions like depression.

One important aspect to note is that the severity of sleep issues directly correlates to the relative amount of anxiety (12). In other words, even if you can’t completely fix your anxiety or stress levels, even improving them a bit can have significant effects on your sleep.

Some common stressful events that lead to sleep issues include:

Poor Sleep Hygiene

The average Western person’s sleep hygiene is not good, and poor sleep hygiene is one of the biggest risk factors of insomnia.

Issues like anxiety or hormone changes are either unfixable or they take a long time. But sleep hygiene can be improved almost instantly, so it’s a no-brainer for most people with sleep issues to focus on at first.

See our complete guide to sleep hygiene for insomnia for full details. In summary, the most important things to avoid are:

Comorbidities (Other Physical Health Conditions)

Any small health issue has the potential to cause a decrease in sleep quality. More severe conditions can cause chronic insomnia if they can’t be resolved.

Here is an incomplete list of conditions that may cause insomnia:


Many health conditions directly cause pain that interferes with sleep.

Even the treatment for these problems can cause sleep problems, although they are usually short-term. For example, insomnia symptoms are common after:


In general, kids sleep well (although there are exceptions).

However, once you age into young adulthood, your risk for sleep problems often rises. Exposure to life stressors like marriage, having children, moving, and work problems can all cause stress, which can then lead to sleep problems. Some research suggests that people aged 20-35 are at highest risk of insomnia (13).

Once most people get to old age, physical health often declines. Taking medications for health problems can cause insomnia as a side effect, as can health problems like poor bladder control.

Exercise Before Sleep

The effect of exercise on sleep isn’t fully understood, and it’s a bit controversial.

If you go back a few decades, people would tell you that exercising shortly before sleeping will worsen sleep.

More recent research shows that intense exercise might, but light exercise likely doesn’t (14).

Evening exercise was not associated with worse sleep. These findings add to the growing body of evidence that sleep hygiene recommendations should not discourage evening exercise.

After a hard workout, cortisol and body temperature can remain elevated, which can impair sleep. But when it comes to a light workout, these aren’t usually problems. For a deeper dive into the research, see our guide to how working out affects insomnia.

Medication Can Cause Insomnia

As we’ve seen, insomnia often develops alongside another disease or condition.

A lot of the time, sleep problems are caused by the medication needed to treat that initial condition.

For example, some people with depression take an SSRI called Celexa and get insomnia as well. In those cases all a physician can really do is give you a different medication to try instead.

In addition, certain medications can cause rebound insomnia, which is essentially just a short-term symptom of withdrawal, but can be very uncomfortable.

Shift Work and Jet Lag

Shift work causes a decrease in sleep quality for most.

In short, it disrupts your circadian rhythm, which essentially controls the timing of biological processes like hormone production. There’s not a fix to these issues other than

Melatonin is a natural sleep aid that can help significantly with no significant side effects in most cases, but it’s not a complete fix (and doesn’t help everyone the same).


  1. Prostate cancer treatments and their side effects are associated with increased insomnia
  2. Energy drink consumption by gender and age
  3. Why is depression more common among women than among men?
  4. Subjective sleep quality in premenstrual syndrome
  7. A Study of Caffeine Consumption and Symptoms: Indigestion, Palpitations, Tremor, Headache and Insomnia
  8. Risk Factors for Incident Chronic Insomnia: A General Population Prospective Study
  9. Relationship Between Added Sugar Intake and Sleep Quality Among University Students: A Cross-sectional Study
  10. Sleep duration and consumption of sugar-sweetened beverages and energy drinks among adolescents
  11. Incidence and risk factors of insomnia in a population-based sample
  12. Place of chronic insomnia in the course of depressive and anxiety disorders
  13. Risk Factors for Incident Chronic Insomnia: A General Population Prospective Study
  14. Does nighttime exercise really disturb sleep? Results from the 2013 National Sleep Foundation Sleep in America Poll

Medical Disclaimer: The information on is not intended to be a substitute for physician or other qualified care. We simply aim to inform people struggling with sleep issues about the nature of their condition and/or prescribed treatment.

About the authorDale is the founder of Snooze University and a sleep researcher. I overcame my sleep issues and now I'd like to help you do the same by summarizing the latest sleep studies for you.