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Why can't I sleep?

Updated: Mar 19, 2021

Difficulty sleeping is a struggle many of us can relate to. Falling asleep in the first place can be tough but staying asleep and getting a sleep of good quality – where you wake up feeling refreshed - are also growing problems. With more of us than ever leading busy, hectic lifestyles and juggling multiple pressures, it’s little wonder our sleep is suffering. When there are things to be done, an early night is often the first thing we sacrifice and many of us are sleeping less and less as we take on more at work and home whilst maintaining some kind of social life. “It’s only a few hours’ sleep”, we may tell ourselves; “I’d rather be tired than have to let someone down”. But the truth is, chronic sleep deprivation may be having a real impact on our health. Prioritising some shuteye could therefore hold the key to reducing illness, improving alertness and managing feelings of stress.

What is sleep?

Sleep occurs in a cycle consisting of five stages. Stages 1 to 4 see a progression from a light to a deep sleep and time spent in these stages is important for the consolidation and storage of memories. These first stages are collectively known as non-rapid eye movement (NREM) sleep. The fifth and final stage of the cycle is known as rapid eye movement (REM) sleep and is the stage at which dreams often occur. Once REM sleep is completed, the sleep cycle will begin again at Stage 1 and continue until the sleeper wakes.

The importance of sleep

Sleep and cognitive function

When we experience sleep deprivation, even just for one night, we may struggle with drowsiness, inability to focus and impaired performance. A 2017[1] study examined this theory in shift workers and reported significantly reduced reactions, vigilance, memory and mathematical ability in those experiencing sleep deprivation.

Sleep and growth & repair

When we are in a deep sleep, the body increases production of proteins needed for the growth and repair of cells. This is a key process that facilities recovery from physical stress such as exercise or injury, as well as from damage caused by psychological and emotional trauma. Just as a rest-day is an important part of an athlete or gym-goer's performance strategy, so is sleep.

Sleep and the immune system

During periods of illness, it is common to feel more tired than usual. This is because illness triggers the immune system to release chemicals known as cytokines into the body. These cytokines are key to an effective immune response, but they also induce feelings of drowsiness and fatigue, most likely to encourage us to rest and conserve energy needed to fight off infection.

Sleep and learning

REM sleep in particular is linked with the ability to learn new skills and retain learned information. A 2015[2] study demonstrated a process by which the brain can rescue and consolidate memories damaged by interference immediately after the learning process. The ability of the brain to ‘rescue’ memories was found to be entirely dependent on REM sleep. Failure to complete REM led to inability to rescue memories in the face of interference and subsequent impairment in the ability to learn new skills.

How can I improve my sleep?

So, it’s clear that sleep is key to healthy functioning of brain and body, but for many of us, getting enough, good quality sleep is a challenge.

If you’re struggling, here are a few simple yet effective strategies you can try to take back control of your sleep cycle:

1. Take a break from screen-time before bed

Do you find you’re often working late at the computer, watching TV or scrolling your phone last thing before you go to sleep? If so, this late-night screen time could be playing a role in your sleep troubles. The blue light emitted from our devices mimics natural light and delays the release of melatonin – the hormone typically released to cause drowsiness. This hormonal change prevents physiological processes designed to send us to sleep, for example lowered heart rate and blood pressure, leaving us with a feeling of wakefulness that makes falling asleep more difficult. The simplest solution is to avoid all devices at least one hour before you plan to go to sleep. Try reading a book instead (a paper back, rather than a Kindle!), or perhaps take a warm shower or bath, listen to relaxing music or do some gentle stretching. If you really need to work on your computer in the evening, invest in a pair of blue light blocking glasses. These effectively prevent blue light from entering your eyes and may help to limit the impact of screen time on your sleep cycle.

2. Control your exposure to daylight when travelling

Our sleep cycle is regulated by the circadian rhythm – a natural, internal process that runs over around 24 hours and is heavily influenced by exposure to daylight. Frequent international travellers experience disruption to this natural sleep and wakefulness cycle, often leading to chronic sleep deprivation and performance decrements. Indeed, research shows that after 16 hours awake; performance may deteriorate to become comparable to someone who is legally drunk. It is best to stay on your native time zone if away for short periods – meaning you should avoid daylight when it would be dark at home and seek artificial light sources when it would be daytime. Bright light therapy offers a solution for those needing to mimic natural light and portable devices that may be packed in luggage are available to purchase. If you are taking a longer trip where it is impractical to avoid switching to another time zone, bright light therapy may also provide some relief from symptoms of sleep deprivation. A 2015 [3] study of aircrew reported improved behavioural alertness following exposure to bright light therapy during duties. This effect was attributed to the suppression of melatonin and subsequent delay in feelings of drowsiness.

3. Stick to a bedtime routine

Our bodies love routine and lack of consistency can wreak havoc on our sleep. Our brain responds to cues in our environment that signal where we should be in the sleep and wakefulness cycle so taking control of these can be a big help in telling our brain that it’s time for bed. The first thing to consider is when you can realistically go to bed and try to make this more or less the same each night. Consistency in this over a few weeks will reset your body clock to a more regular rhythm and train your brain to start feeling tired at the same time each evening. If you are unable to stick to a regular bedtime (e.g., if you’re a shift worker), there are still steps you can take to ensure your brain is receiving the right information before bed. Try developing a short bedtime routine that you perform every night before you go to sleep. An example might be a shower, followed by brushing your teeth and then reading a few pages of a book. This routine should not include any high intensity exercise, caffeine, alcohol or screen time as these can all have a negative effect on sleep.

4. Avoid excessive alcohol and coffee consumption

Alcohol is often credited with assisting sleep and is a common form of self-medication for those who struggle with sleep conditions. Whilst it’s true that alcohol can help you fall asleep, it is unlikely that you will experience a sleep of good quality from this strategy. Alcohol consumption before bed has been linked to a disturbance in the restorative qualities of sleep and a reduced amount of time spent in the deeper, REM stage [4]. It is therefore likely that an alcohol-induced sleep will leave you feeling tired and unrefreshed. In contrast to alcohol, caffeine is often used as a means to keep us awake when we need an extra boost. Caffeine is indeed an effective stimulant and can be used strategically to enhance alertness and performance in daytime functioning. Excessive consumption of caffeine - or consumption later in the day - however, may lead to difficulty getting to sleep, as well as reduced sleep quality due to effects on receptors in the brain [5]. Caffeine has a long half-life meaning it may continue to impact sleep long after your last coffee; even if you have your last cup at midday, you will still have one quarter of its caffeine content in your system by midnight. It is therefore a good idea to switch to decaf or non-caffeinated drinks after late morning in order to safeguard the quality of your sleep.

5. Keep a notepad and pen by your bed

We can lose sleep when we find it difficult to switch off. This can be due to having a number of tasks that remain incomplete, or due to worry or stress. The dark and quiet of night-time can be when thoughts start to surface and, in the absence of distractions, we my start to ruminate over things we have no way of resolving at the time. A good remedy for worry and rumination is to keep a notepad and pen by your bedside. When you notice yourself starting to think about unresolved tasks or issues, write your thoughts down on your pad of paper. Your notes will be there as a prompt the next morning if there is something you must remember or need to do, and this process acts as a form of venting for worries and concerns, making it easier to fall asleep without burden.

If you are struggling with your sleep, read through these suggestions again and pick one or two that you can try. Daily life can be hectic and the small things we do each day can be chipping away at the health of our sleep, so introducing one or more of these strategies may be a big step towards regaining control over your sleep cycle. This in turn will have a significant impact on your overall health, wellbeing, and performance, allowing you to unlock your potential.

Sophie Fox

Performance Nutritionist and Health Adviser


[1] Kaliyaperumal, D., Elango, Y., Alagesan, M., & Santhanakrishanan, I. (2017). Effects of sleep deprivation on the cognitive performance of nurses working in shift. Journal of Clinical and Diagnostic Research, 11, CC01.

[2] McDevitt, E. A., Duggan, K. A., & Mednick, S. C. (2015). REM sleep rescues learning from interference. Neurobiology of Learning and Memory, 122, 51-62.

[3] Brown, L., & Whitehurst, G. (2015). The Effects of Bright Light Intervention on Flight Crew Behavioral Alertness and Cognitive Fatigue. In 18th International Symposium on Aviation Psychology (p. 608).

[4] Sagawa, Y., Kondo, H., Matsubuchi, N., Takemura, T., Kanayama, H., Kaneko, Y., ... & Shimizu, T. (2011). Alcohol has a dose‐related effect on parasympathetic nerve activity during sleep. Alcoholism: Clinical and Experimental Research, 35, 2093-2100.

[5] O’Callaghan, F., Muurlink, O., & Reid, N. (2018). Effects of caffeine on sleep quality and daytime functioning. Risk Management and Healthcare Policy, 11, 263.


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