Sleep is just as critical to our body as other basic functions of survival like eating, drinking, and breathing. Sleep is needed for a number of reasons, including energy conservation, restoration of our tissues and cognitive function, emotion regulation, and immune health.
Many of the restorative functions of sleep are specifically associated with non-REM sleep, which is the stage of deep sleep that leaves us feeling refreshed and alert. The body has multiple systems regulating our sleep-wake cycle and our journey through the cycle of sleep stages. These processes work together to ensure we get deep, restful sleep, and have energy throughout the day.
Lifestyle choices, such as the decisions we make relating to our diet and exercise routines, can impact these systems for better or for worse. For example, a high-calorie diet can disrupt circadian rhythms, and a lack of nutrients like calcium, magnesium, and Vitamin D may negatively affect sleep duration. In contrast, healthy behaviors like physical exercise contribute to better sleep quality and increased energy.
Sleep satisfaction, which refers to one’s subjective perception of their quality of sleep, can also impact energy levels. One study found that poorer subjective sleep quality predicted next-day fatigue in individuals with chronic fatigue syndrome.
While there is no substitute for a good night’s rest, there are a few things you can keep in mind to ensure you get restful sleep to feel satisfied and give you the energy you need.
One of the prominent theories on sleep function posits that sleep serves to conserve and restore energy. Since the introduction of this theory, research has explored the roles of two chemicals in particular – glycogen and adenosine. Glycogen is involved in storing energy in the brain, and glycogen levels have been shown to decrease during wakefulness. Sleep deprivation is also linked to decreased glycogen levels, and glycogen levels are restored during sleep. Adenosine, on the other hand, accumulates during waking hours and promotes sleepiness. It is proposed that glycogen reduction, while we are awake, leads to a build-up of adenosine, which in turn helps us sleep and restore lost glycogen. This type of feedback loop involving chemicals that regulate the sleep-wake cycle is known as sleep homeostasis.
The relationship between lifestyle choices and sleep also impacts our energy balance. Energy balance is used to describe the net outcome of energy intake (food consumption) with energy expenditure (activity). Insufficient sleep has been linked to an imbalanced increase in energy intake over expenditure, which leads to a positive energy balance and weight gain. Sleep quality may also moderate the relationship between physical activity and feelings of fatigue. This indicates that diet, exercise, and sleep all interact and influence our feelings of energy and our energy balance.
Some people experience higher energy levels at night, making it difficult to fall asleep and get the rest they need. This can be especially troubling if demands like work or school still require them to wake early, and therefore get insufficient sleep.
Delayed Sleep-Wake Phase Disorder, which is a disruption in circadian rhythm, may be the cause. Circadian rhythms are 24-hour cycles controlled by certain genes called circadian clock genes. They help us align our sleep-wake cycle with environmental factors, like the natural 24-hour cycle of light and dark that coincides with day and night.
Circadian rhythms work together with the chemicals in our body that control sleep homeostasis and keep us on a regular schedule. However, circadian rhythms are still vulnerable to disruption from unhealthy lifestyle habits, underlying medical conditions, or even genetic predispositions. A circadian rhythm that has fallen out of sync with the cycle of day and night can lead to sleep deprivation, energy imbalances, and metabolic disease. Circadian disruptions have also been linked to cardiovascular diseases, sleep disorders, and cancer.
Diabetes risk is of particular concern for those who suffer from circadian disorders. This is because circadian rhythms regulate glucose levels, and misaligned rhythms result in increases in glucose and impaired glucose metabolism, which are risk factors for diabetes and obesity. Reduced sleep quality caused by circadian disorders can also influence unhealthy exercise and eating patterns, which exacerbate diabetes risk.
There is no replacement for a good night’s rest. However, if you find yourself struggling with daytime sleepiness, there are a few things you can do to improve your energy levels.
One short-term solution is napping. Even a brief nap can improve neurobehavioral performance and relieve the pressure to sleep left by lack of sleep. However, naps can also make it difficult to sleep at night, leading to a risk for sleep loss the following day. That is why the best thing you can do for your sleep and energy levels is practice regular habits that ensure you obtain consistent, restful sleep night after night.