Coffee accounts for 54% of all caffeine consumption in the world.
When drinking coffee, the caffeine from it begins to affect your body quickly within 30 to 60 minutes. It can last up to three or five hours in your body, giving you an energy boost for quite some time. But it can take up to twelve hours for your body to metabolize an 8 ounce cup of coffee.
The NHS (National Health Service) does advise it is alright to drink coffee as a part of a balanced diet, but when consumed too late in the evening can affect our sleep cycle.
Rob Van Dam, a professor at the National University of Singapore recommends those who have sleep troubles to cut down on the amount of caffeine they are consuming.
“It’s really something every individual has to experiment with for themselves - how much caffeine they drink and when they drink it,” Van Dam mentions.
In a 2016 systematic review of research on coffee, caffeine and sleep concluded that individuals will respond differently to caffeine based on a variety of factors, including age, sensitivity levels, regular coffee and caffeine intake, time of consumption, and genetic variability.
Natural Sleep Schedule
According to the Sleep Foundation, caffeine can impact the onset of sleep and reduce sleep time, efficiency, and satisfaction levels. Caffeine notably reduces the time of slow-wave sleep, which is the stage of deep, restful sleep that leaves us feeling refreshed and alert in the morning. When caffeine interrupts sleep it can lead to sleep deprivation the following day.
Too much caffeine can also affect your internal clock and central nervous system. This is called the human circadian clock. It is a natural, biological clock that is made up of circadian rhythms. They are physical, mental, and behavioral changes that follow a 24 hour cycle. The process usually responds to light and dark.
As the sun rises and the day begins, your energy starts to revive as your body temperature rises. This helps your body become awake, increasing alertness and sharpness. When the day continues on, around the afternoon you may go into a slump, creating daytime sleepiness. This can be helped with a snack, especially between 1:00pm and 3:00pm. As the sun goes down, melatonin is naturally activated, telling your body it’s time to rest.
Those who are dependent on caffeine due to coffee consumption result in daytime dysfunction and increased levels of night-time disturbance. Normal sleep is divided into non-rapid eye movement (NREM) and rapid eye movement sleep (REM). NREM sleep is further divided into three stages:
Stage one is when you fall asleep right away and can easily be woken up.
Stage two is when you begin slow-wave brain activity, last 30 to 60 minutes.
And stage three is when you are in a deep sleep.
After 80 to 100 minutes of stage 3 NREM, your brain is going into the REM sleep cycle which can last up to 90 minutes. This is where the brain and body can get the most rest and dreams occur. When caffeine is consumed too close to when the body naturally produces melatonin, these cycles will be disrupted.
Effect of Caffeine on Sleep in Young People
Research suggests that caffeine helps restore levels of alertness and counteracts cognitive performance due to sleep deprivation. Nevertheless, caffeine may produce damaging effects on adolescents’ sleep schedules.
A survey looking at adolescent caffeine use, 95% of teens used caffeinated drinks, like energy drinks, black teas, and coffee to stay awake during school days. 33% of those teens fell asleep during class. Caffeine reduces a teenager’s functional process throughout the day, resulting in daytime sleepiness rather than daytime alertness.
Teenagers who drink coffee expect more energy when consumed due to the caffeine, but they are more likely to receive drowsiness during the day instead of energy, resulting in improper sleep schedules. This affects how students are doing in class, with after school activities and their moods throughout the day.
No Coffee Before Bed
One study shows how taking caffeine zero, three, and six hours before bedtime. The results showcase how consuming caffeine 6 hours before bed can reduce sleep time by one hour. When study participants consumed caffeine within zero to three hours before bed, they reported no sleeping problems, but did not realize their sleep was disrupted.
The Sleep Foundation recommends not drinking any coffee or caffeine-filled substances at least 6 hours before bed due to it reducing your rest cycle and leaving you feeling fatigued in the morning.
They also suggest that when consuming too much caffeine it can cause insomnia symptoms or even worsen pre-existing insomnia. Consuming caffeine to stay awake at night can lead to sleeplessness, anxiety, frequently waking up in the middle of the night, and overall, decrease a good night’s sleep.