Sleep Deprivation: Feeling Better Or Just Wired?

Sleep is a cornerstone of good health, and insufficient sleep can have a wide range of negative impacts on the body and mind. However, some people report feeling more energised and alert after a night of poor sleep. This may be due to a variety of factors, including a surge in cortisol and adrenaline, the brain's reward system firing up, subjective adaptation to sleep loss, improved sleep hygiene, or other external factors. While feeling more energised after a night of poor sleep, individuals may actually be performing worse and their health may be suffering.

Cortisol and adrenaline levels increase

When you don't get enough sleep, your body's cortisol production goes into overdrive. Cortisol is often referred to as the body's "caffeine". It is a stimulant that your body produces naturally. When you engage with something or someone interesting, your cortisol levels increase, enabling you to focus and engage in a lively manner. However, when you don't get enough sleep, your cortisol production remains elevated instead of decreasing naturally, giving you the illusion that you feel better with less sleep.

Cortisol is your body's stress hormone, produced and released into your bloodstream by your adrenal glands. When your body doesn't get enough sleep, it operates on borrowed energy, relying on cortisol and caffeine to function. This results in an increase in stress levels and a loss of ability to remain calm and in control. Elevated cortisol levels can have serious consequences for your health and well-being.

In addition to cortisol, your body also produces adrenaline when you are sleep-deprived. The sympathetic nervous system, responsible for active behaviour and fight-or-flight responses, takes over in situations of perceived danger. For example, if you encounter a bear while hiking, your sympathetic nervous system pumps cortisol and adrenaline through your body, signalling that escaping the bear is the top priority. Adrenaline gives you a burst of energy and sharpens your senses, preparing you to either fight or flee the perceived threat.

While the surge of adrenaline and cortisol can make you feel more alert and energetic in the short term, it comes at a cost. Prolonged elevated levels of these stress hormones can lead to negative health outcomes, including weight gain, heart disease, anxiety, signs of premature ageing, and more. Additionally, the increase in cortisol and adrenaline interferes with the functioning of the parasympathetic nervous system, which is responsible for "rest and digest" or "rest and repair" functions. This system takes care of crucial tasks such as repairing the gut lining, destroying aberrant cells, and absorbing nutrients. However, it can only do its job effectively when the body is in a state of rest, which is disrupted when cortisol and adrenaline levels are high due to sleep deprivation.

In summary, while you may feel more alert and energetic in the short term due to increased cortisol and adrenaline levels, this comes at the cost of your long-term health and well-being. Adequate sleep is crucial to restore balance and allow your body to carry out its essential functions optimally.

The brain's reward system fires up

Research has shown that sleep loss increases reactivity in the brain's reward system. This means that when you're sleep-deprived, you may react better to both positive and negative stimuli. You may also experience giddiness or euphoria, making you feel better when you sleep less.

Sleep loss can even improve the moods of those with depression. Research has shown that an all-nighter can improve depressive symptoms in 40% to 60% of cases. However, these improvements disappear when people get more sleep. It's important to note that sleep deprivation is linked to hyperactivity, impulsivity, and symptoms that mimic ADHD. While you may feel more energetic, this extra energy is not sustainable and could be similar to a manic state.

Additionally, when you don't get enough sleep, your body produces more of the alertness-boosting hormones cortisol and adrenaline to get you through the day. While these hormones may give you a false sense of energy, they can also lead to difficulty sleeping at night as you remain stuck in fight-or-flight mode, resulting in even more sleep loss. High cortisol levels can cause various issues, including difficulty concentrating, weight gain (especially belly fat), anxiety, and depression.

Furthermore, the longer you stay awake, the more sensitive and amped up your brain becomes. One study found that the excitability of the frontal cortex, a part of the brain, increases with time awake and decreases when you get more sleep. This heightened brain activity may contribute to the feeling of having more energy despite a lack of sleep.

While you may feel more energized and alert after a sleepless night, it's important to remember that your performance, health, and well-being are likely taking a hit. Sleep deprivation can lead to impaired cognitive function, increased risk of health issues, and negative side effects such as a lowered immune system, weight gain, and heart disease.

Dopamine levels increase

Dopamine is a neurotransmitter that modulates wakefulness by exerting a wake-promoting action. Drugs that enhance dopamine signalling through dopamine transporter (DAT) blockade, such as methylphenidate and modafinil, or by releasing dopamine (e.g. amphetamine) increase wakefulness in human subjects. Similarly, mice with a deletion of the DAT gene, resulting in enhanced dopamine neurotransmission, display increased wakefulness. Conversely, patients with Parkinson's disease, which involves dopamine depletion, experience excessive daytime sleepiness.

Sleep deprivation has been found to increase dopamine levels in the human brain. Specifically, one night of sleep deprivation has been shown to increase dopamine in the striatum and thalamus, which are involved in motivation, reward, and alertness, respectively. This increase in dopamine may be a compensatory response to increased sleep drive in the brain, promoting wakefulness. However, the rise in dopamine may not be sufficient to overcome the cognitive deterioration induced by sleep deprivation and may even contribute to it.

In support of this, a study found that sleep-deprived mice showed a significant decrease in D1 receptor density in the striatum, with no change in D2 receptor density, and a significant increase in D3 receptor density. This pattern of changes in dopamine receptor density was not observed in mice subjected to restraint stress, suggesting that it may be specific to sleep deprivation rather than a general response to stress.

Another study found that sleep deprivation decreased D2/D3 receptor availability in the ventral striatum, which was associated with reduced alertness and increased sleepiness. However, the findings suggest that this decrease in receptor availability may be due to D2/D3 receptor downregulation rather than increased dopamine levels, as methylphenidate-induced increases in dopamine did not differ between rested sleep and sleep deprivation.

In summary, while sleep deprivation has been shown to increase dopamine levels in the human brain, which may promote wakefulness, the cognitive deficits associated with sleep deprivation may not be fully compensated for by this increase in dopamine. Additionally, changes in dopamine receptor density observed in sleep-deprived mice suggest that sleep deprivation may specifically alter dopamine circuits in the brain.

You subjectively adapt to sleep loss

Our brains are good at tricking us. When we don't get enough sleep, we can subjectively adapt to some of the effects of chronic sleep deprivation.

We feel fine on less sleep, but we're not really doing fine at all. One study found that participants' performance on cognitive tests got significantly worse the more sleep-deprived they became. But their ratings of sleepiness only increased slightly at first and then evened out.

The study stated, "Sleepiness ratings suggest that subjects were largely unaware of these increasing cognitive deficits, which may explain why the impact of chronic sleep restriction on waking cognitive functions is often assumed to be benign."

Another sleep study found people who said they got enough sleep slept more than three hours longer when they got the chance — meaning they were probably sleep deprived and didn't know.

And you might simply be missing the signs of sleep deprivation. It's not just low energy — sleep loss can cause everything from weight gain to acne, digestive issues to mental exhaustion. It's easy to blame a bad diet or stress over poor sleep for these symptoms.

You've improved your sleep hygiene

Sleep hygiene refers to the habits and practices that can help you get better sleep. It includes both your sleep environment and your behaviour during the day and before bedtime.

Set a consistent sleep schedule: Try to go to sleep and wake up at the same time every day, even on weekends. This reinforces your body's sleep cycle and can make it easier to fall asleep and wake up.

Create a relaxing bedtime routine: Engage in relaxing activities about an hour before bed to help you unwind and signal to your body that it's time to sleep. This could include taking a warm bath, reading a book, listening to soothing music, or meditating.

Optimise your bedroom: Make your bedroom a calm and comfortable space. Keep the temperature cool, preferably around 65 degrees Fahrenheit. Use comfortable bedding, pillows, and mattresses. Block out light with curtains or an eye mask, and minimise noise with earplugs or a white noise machine.

Limit screen time before bed: The blue light emitted by electronic devices interferes with melatonin production, making it harder to fall asleep. Keep your phone out of reach, and avoid screens at least an hour before bedtime.

Exercise regularly: Regular exercise can improve your sleep quality. However, avoid exercising within a few hours of bedtime as it may increase your energy levels and body temperature, making it harder to fall asleep.

Limit caffeine and alcohol intake: Caffeine is a stimulant that can keep you wired when you want to sleep. Avoid caffeine in the afternoon and evening, and be mindful of your tolerance levels. Alcohol can also disrupt your sleep architecture, so it's best to moderate your consumption and avoid it close to bedtime.

By improving your sleep hygiene, you can fall asleep faster, wake up less frequently, and feel more rested and energised during the day.

Frequently asked questions