Coffee consumption and mental performance – Part 3

Print this page

Here is some further information covering research on the topic of coffee consumption and mental performance. This post focuses on the area of coffee consumption and sleep.

Caffeine and sleep
Sleep in humans is affected by caffeine intake. An association between the daily intake of caffeine, sleep problems and daytime sleepiness has been found, including difficulty falling asleep, shorter total sleep time, longer periods of light sleep and shorter periods of deep sleep, as well as more frequent awakenings. This can be experienced at levels equivalent to those of a single cup of coffee.

These effects depend not only on the amount of caffeine ingested at bedtime, but also on the quantity of caffeine consumed throughout the day.

Sensitivity to the effects of caffeine is variable. For example, the effects of caffeine on sleep are smaller in subjects who usually ingest caffeine than they are in infrequent coffee drinkers. In addition, genetic variations may also play a role.

Age may affect sleep quality
Only a few studies have evaluated the age-related effects of caffeine on sleep. In one study, caffeine produced similar effects in young, 20-30 years, and middle aged subjects, 45-60 years. In another, middle-age subjects appeared to be more sensitive to the effects of caffeine than younger subjects. Age and caffeine both decrease rapid-eye movement sleep. Therefore the collective effects of age and caffeine may further disrupt sleeping patterns.

Caffeine abstinence may improve sleep patterns
A large review of caffeine abstinence and sleep quality concluded that abstention from caffeine for a whole day could improve sleep quality. Caffeine withdrawal was shown to extend sleep duration, improve sleep quality and make it less difficult to fall asleep.

Caffeine intake and lack of sleep in teenagers
Although caffeine restores wakefulness and counteracts a decline in mental performance due to lack of sleep, it may produce disadvantageous effects on subsequent sleep, resulting in daytime sleepiness, which might be a matter of concern particularly in young people. Many teenagers stay awake late at night using numerous forms of technology, and use caffeinated beverages to help them stay awake.

One study of young people found that sleep was directly related to multi-tasking, with those doing the greatest amount of multi-tasking having the least amount of sleep. Caffeine intake was also found to be 76% higher in teenagers who fell asleep at school. This implies that those teenagers are not fully functional throughout the day because of excessive daytime tiredness, and not because of the effects of caffeine ingestion.

Similarly, another study found that adolescents who drank more caffeinated drinks expected more energy improvement from those drinks. They also got up earlier, reported greater daytime sleepiness and consumed more caffeine to get through the day.

Caffeine, jet lag and shift work
Caffeine may be effective at improving performance of people aged 40 or under, who work shifts or suffer jet lag. Further research is however required in older individuals.

Advice for jet lag on short stopovers of 1-2 days is to combine thoughtful naps with moderate caffeine intake and short-term hypnotics, to help maintain alertness and assist sleep.

Finally, the well-established advantageous effect of caffeinated coffee on mental performance has recently been confirmed by EFSA, which states that a cause and effect relationship has been established between a 75mg serving of caffeine, the amount in approximately one regular cup of coffee, and both increased attention and alertness, mainly in situations of low arousal or stimulation.

In conclusion, Daily caffeine intake does affect sleep patterns; however, these effects depend on the quantity of caffeine consumed over the totality of the day and vary with individuals’ genetic backgrounds. Individuals who do experience sleep problems following consumption of caffeinated coffee may decide, or be advised, to switch to decaffeinated products in the afternoon/evening.

For more information on coffee and mental performance, and to view information sources, click here.

This information is intended for Healthcare professional audiences.
Please consider the environment before printing.