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Why Can't I Sleep? 6 Reasons You're Tired but Can't Get to Sleep

Why Can't I Sleep? 6 Reasons You're Tired but Can't Get to Sleep

Feeling tired yet unable to sleep can be an extremely frustrating experience. When, regardless of how tired you feel at night, you simply cannot fall or stay asleep, you can rapidly become irritable or stressed and, if this becomes a chronic condition, it can affect your mental and physical health.

Sleeping badly at night leaves you feeling exhausted, and can take a toll on productivity, relationships or concentration. But it also deprives your body of much-needed rest and reparative biological processes. When you are asleep, your heart and muscles relax, allowing them to rest, repair and recover — decreasing the risk of them becoming overworked — and your brain performs essential chemical and hormonal rebalancing.

There are various reasons why you may be having trouble sleeping, from aspects of your lifestyle to medical conditions that inhibit sleep. Here, we take a look at these factors, and how you could improve your sleep hygiene.

Stress and anxiety

Laying awake at night, going over worrying or negative thoughts in your mind, is one of the main reasons why people find falling asleep difficult. It’s easy to do however, you could be worried about personal things such as finances, relationships with friends, partners or work colleagues or even wider troubles such as the environment.

These anxious thoughts can trigger cortisol, the hormone that promotes wakefulness and alertness — the antithesis of the relaxation needed for sleep. Cortisol will work to reverse the effects of your sleep hormone, melatonin, preventing you from getting to sleep.i Furthermore, sleeplessness can increase anxiety, perpetuating a vicious cycle. Stimulation of appropriate hormones is essential in getting to sleep, find out how melatonin and serotonin help you fall asleep here.  

Hormonal imbalances

For women, hormonal imbalances can cause significant disruption to healthy sleep patterns. Menstruation and menopause trigger rises and drops in certain hormones, which can affect your sleep hygiene. Just before a woman starts her period, for instance, the drop in progesterone causes body temperature to fluctuate. This, in turn, can reduce the amount of REM sleep (rapid-eye movement) — the restorative stage where most dreaming takes place, memories are entrenched, and learning is consolidated.

As a woman enters menopause, on the other hand, oestrogen plummets suddenly, triggering several symptoms that may contribute to sleeplessness, particularly hot flushes.iii


Need five, strong coffees to get you through the day? It’s possible your caffeine habit is keeping you up at night. A stimulant, caffeine is known for extending sleep latency (the time it takes to fall asleep), diminishing sleep efficiency, reducing total sleep time, and worsening sleep quality.iv

Since it has a half-life (the time it takes for its initial level of impact to reduce by 50 per cent) of six hours, drinking anything caffeinated past noon means you’ll still have caffeine in your system around bedtime. One study has even revealed that drinking coffee 6 hours before bedtime can reduce sleep by a whole hour.v

Blue light from electronic devices 

Your body operates via a 24-hour internal clock, known as your circadian rhythm, which uses darkness and light signals. Light cues activity, while darkness cues rest. Watching TV, looking at your laptop or tablet or checking your phone late at night disrupts this natural biological rhythm.

Using electronic devices at night skews the production of your sleep hormone, melatonin, which is secreted a couple of hours before you go to bed. The blue light glaring from your gadgets tricks the brain into thinking it should be awake, making it feel energised and stimulated.vii Learn more about how you can reduce the impact of blue light on your sleep pattern here.


According to a study published by the UK’s Mental Health Foundation, nearly a third of Britons suffer from some form of insomnia.viii Insomnia is typically defined as experiencing difficulty falling asleep, maintaining sleep throughout the night, or waking up too early in the morning.

Insomnia can persist for several days, a couple of weeks, or even months at a time.  Usually, it’s accompanied by daytime sleepiness, fatigue, low energy, irritability, poor work or school performance, loss of motivation, impulsive or aggressive behaviour, and mood swings. Certain medical conditions, low mood, anxiety, and stress are some of the most common causes of chronic insomnia.

Circadian rhythm disorders

Circadian rhythm disorders manifest from a desynchronisation between the light-darkness cycle and the 24-hour internal sleep-wake cycle. Jet lag is a prime example of this. In light of the circadian mismatch, people with such disorders often complain of insomnia and excessive sleepiness during the day. Overtime, this can have a knock-on effect on work, social, and personal commitments.

If you work night shifts, you’re at a greater risk of experiencing a circadian rhythm disorder. That’s because your odd work schedule can leave you fighting against the dials of your internal body clock. Indeed, humans — as diurnal creatures — are hardwired to operate during the day and sleep at night. That’s why the traditional 9-5 working hours are the most conducive to our sleep-wake cycle; anything too far outside this window can disrupt and confuse the body’s internal body clock. Learn how to recalibrate your circadian rhythm if you’re a night shift worker here.

Whilst some of these factors can be frustrating and difficult to manage, by changing a few aspects of your lifestyle can help improve your sleep quality and make you wake up feeling energised and refreshed.

For more information on how you can achieve optimal sleep hygiene, feel free to browse the rest of our sleep health hub for more guidance on sleeping soundly.


  1. Sleep and anxiety disorders. Dialogues in clinical neuroscience. 5(3), 249–258.

  2. & Sleep, Hormones, and Circadian Rhythms throughout the Menstrual Cycle in Healthy Women and Women with Premenstrual Dysphoric Disorder. International Journal of Endocrinology. 1-17.

  3. Menopause & Sleep - National Sleep Foundation. Available online:

  4. , , , , , , , , & Effects of vigorous late-night exercise on sleep quality and cardiac autonomic activity. Journal of Sleep Research. 20(1pt2), 146-153.

  5. , , & Caffeine Effects on Sleep Taken 0, 3, or 6 Hours before Going to Bed. Journal of Clinical Sleep Medicine.

  6. Caffeine, the circadian clock, and sleep. Science. 349(6254), 1289-1289.

  7. , , & Research progress about the effect and prevention of blue light on eyes. International journal of ophthalmology. 11(12), 1999–2003.

  8. NHS.UK. Sleep problems in the UK highlighted. Available online:


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Our Author - Olivia Salter


Olivia Salter has always been an avid health nut. After graduating from the University of Bristol, she began working for a nutritional consultancy where she discovered her passion for all things wellness-related. There, she executed much of the company’s content marketing strategy and found her niche in health writing, publishing articles in Women’s Health, Mind Body Green, Thrive and Psychologies.

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