A study done by the University of Edinburgh by researchers from the Sleep Medicine Department found that taking coffee 6 hours before bed affected your sleep cycle. According to Reneta Riha, the lead study author, reducing coffee intake six hours before your bedtime could reduce the impact on a person’s sleep-wake cycle. Riha states that coffee is taken by about 80% of the world’s population to increase alertness, concentration and wakefulness. For this reason, knowing when and what amount of coffee to take is vital for the amount and quality of sleep you get.
However, researchers also found that taking coffee after waking up can increase your alertness and concentration, which can be helpful for shift workers who have to keep adjusting to a new sleep-wake cycle constantly.
Researchers discussed the sleep-wake cycle in their report. This cycle, also known as the circadian rhythm, regulates body functions within a cycle of 24 hours. It syncs up with the planet’s light and dark cycles hence why people are affected by moving to a different time zone.
A separate study found that taking 3 cups of coffee can improve cognitive responses of the brain when you have a poor sleep. This is especially helpful for people with an abnormal sleep cycle, such as shift workers. However, it only lasts three days and will eventually negatively impact the duration and quality of sleep.
The researchers at the University of Edinburgh found that taking 75mg of caffeine can help improve your alertness, concentration and attention. Most people can take up to 400mg with the same benefits. Its effects on the body are determined by the speed at which it is metabolised.
Different people have a different caffeine sensitivity. Your caffeine sensitivity should be considered when deciding the daily amount of caffeine you should take. The amount you take in a day will determine your sleep duration and quality. If you find that taking coffee later in the day affects your sleep, you should switch to low caffeinated drinks in the afternoon.