Have you ever wondered how nighttime coffee stops you from dozing off? A group of researchers has figured out the answer.
According to a new study, a double espresso can prolong your waking time by tweaking your internal body clock: it delays the creation of a hormone known as melatonin by as long as 40 minutes.
According to National Sleep Foundation, human sleep is primarily controlled by the amount of light the eyes perceive since it helps stimulate a nerve pathway from the eyes to a part of the brain called hypothalamus. Within it is the suprachiasmatic nucleus (SCN), which controls other hormones that promote wake-sleep cycle such as temperature.
Melatonin, on the other hand, is produced by many parts of the body but mostly by the pineal gland of the brain. At night, SCN activates it, so the hormone is secreted into the bloodstream at high levels, making the body more conducive to sleeping.
For the study, they recruited 5 participants who were exposed to placebo, bright or dim light, or double espresso over the course of 49 days in a light-controlled sleep lab in University of Colorado-Boulder. Those who were drinking coffee were less likely to fall asleep promptly despite the dim light.
They found out its ability to alter the production of hormone and other biochemical processes that promote sleep by testing the effects of coffee on cultured cells.
Although they didn't give any specific suggestions on how to drink coffee, Dr. John O'Neill, one of the co-authors, when interviewed by BBC, recommended that if a person is stressed or tired after a long day, he might want to skip drinking coffee late at night or sipping it at least a few hours before hitting the bed.
Nevertheless, late-night coffee can still be helpful for people who want to get over jet lag easily as well as for those who end up waking up too early.