It’s Daylight Saving Time and I Need Coffee

It is the weekend after the start of Daylight Saving Time. This “spring forward” in time meant that I started leaving the office before the sun sets, which is good, but I really didn’t like the “loss” of an hour of sleep last weekend and don’t like having to leave for the office in the dark again for a few more weeks. There has been a recent move by the state of Florida to end the switch and just keep Daylight Saving Time all year, despite the fact that recent surveys indicate that most Americans approve of the twice yearly time change.

A strong case against the biannual time change can be made on both economic and health grounds. It doesn’t seem to save energy in our 24/7 world and the impact of the time change is felt in many negative ways such as temporarily increased rates of heart attacks and motor vehicle accidents. Another common impact of the change is the increased need of many to use larger amounts of a mild stimulant, most often in the form of coffee. You may even have seen the Facebook meme about the various sizes of coffee cups that range from “tall” to the bucket sized “the day after daylight saving time starts”. Since coffee is so important to so many of us when it comes to coping with this sleep loss and improving our mental functioning, we should take a moment to consider what it is that makes coffee so effective. There are two types of constituent chemicals found in coffee that account for much of its appeal.

One major source of coffee’s appeal is its smell and taste. Caffeine, the stimulant drug that is the main reason why people use coffee, is a bitter substance (Arnaud, 1987) and would not be palatable on its own. The major chemicals that contribute to the taste and smell of coffee are known as terpenes. These organic chemicals are manufactured by plants and have a generally strong smell that may be useful for protecting the plant against being consumed by animals. The chemistry of these chemicals in coffee is extremely complex. Two that have been identified and studied for their impact on taste quality are cafestol and kahweol. Their ratio has been compared with the rating of quality given by professional coffee tasters. When the ratio of cafestol to kahweol was 1:2 or greater, the coffee was judged to be of better quality than at lower ratios. To some degree, these and other terpenes in coffee mask the taste of the bitter caffeine.

Caffeine has a number of well-known effects that make it so highly prized that it is the world’s most used psychoactive drug. Caffeine increases alertness and thus can increase the time it takes to fall asleep as well as reduce the amount of deep sleep obtained during the night (Epstein, 2007). Individuals vary considerably in their sensitivity to the effects of caffeine. Its half-life is about 3 to 5 hours and so a large dose can remain in the system for a long time. Because of its alerting effect, it is extremely useful for waking up in the morning and starting the day’s activities. In fact, it has been studied for its potential to increase functioning among military personnel (Institute of Medicine, 2001).

Typical doses of caffeine are between 100 and 500 mg (Feldman, Meyer, & Quenzer, 1997). At this level caffeine has the effects of increasing arousal, decreasing sleep, and reducing fatigue. Higher doses than this can cause muscle tension and anxiety. Anyone who has rapidly consumed an extra-large, extra strong coffee is probably aware of this effect. This effect is so strong that people suffering panic disorder may experience a panic attack in response to consuming caffeine. Many people consume caffeine in coffee on a daily or near-daily basis. A still unresolved issue is whether caffeine actually enhances attention and performance, or if it just decreases the effects of caffeine withdrawal from the previous day. While there probably is something to be said for the effect of suppressing withdrawal symptoms, which for a stimulant drug would be increased fatigue and low mood, it seems most likely that caffeine does generally improve cognitive functioning, if it is not overused. There are FDA required limits on the caffeine content of drinks and tablets. For drinks such as soda this is 65 mg per 12 oz drink and for tablets it is 200 mg.

It is theoretically possible to die from a caffeine overdose. This has been studied in animals. In humans it is possible, depending on body size and susceptibility to its effects, to have uncomfortable effects at doses as low as 50 – 100 mg. But how much would it take to kill an adult human? It appears to be about 150 mg/kg of body weight. This amount would kill about 50% of people who ingested it, if not treated medically. Given body weights of 110 to 175 pounds, the lethal range would be about 7,500 to 12,000 mg. With a fairly stiff cup of coffee containing 200 mg of caffeine this would require drinking 37 to 60 cups of coffee, rapidly. This would essentially be impossible. Consumption of a bottle of 200 mg caffeine tablets, on the other hand, could potentially reach this lethal dose. A number of such unfortunate cases have been reported.

Caffeine appears to primarily be effective because of its action as an antagonist of adenosine at the purine receptors in the brain (Stahl, 2013). As the brain is active during the day, levels of adenosine gradually rise, resulting in increased sleepiness. Adenosine is the major neurochemical regulator of the increasing drive for sleep over the course of the day and works by inhibiting the excitatory neurotransmitters acetylcholine and glutamate (Roehrs, Carskadon, Dement, & Roth, 2011). Caffeine blocks the effects of adenosine. This has an alerting effect because the adenosine receptors are coupled with certain postsynaptic dopamine receptors (D2). Dopamine has a stimulating effect at the D2 receptors. When adenosine binds to the purine receptors the D2 receptors have reduced sensitivity to dopamine. By preventing the binding of adenosine to these receptors the effect of dopamine D2 receptors is enhanced. As time goes on caffeine is metabolized and eliminated from the body through the cytochrome P450 system, specifically by the enzyme 1A2.

Because of this complex interplay of neurotransmitters and neural pathways, coffee with its stimulant drug caffeine, is able to increase alertness and alleviate, if temporarily, some of the sleepiness and low mood that can accompany the time change and its (grudgingly) lost hour of sleep.

Source: "Yin and Yang" by Klem - This vector image was created with Inkscape by Klem, and then manually edited by Mnmazur.. Licensed under Public Domain via Wikimedia Commons -