The Link Between Caffeine and Sleep

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The Link Between Caffeine and Sleep

Caffeine can be found in many different drinks and foods like tea, coffee, chocolate and soft drinks. It is also found in some medications.

Caffeine promotes alertness by inhibiting chemicals in the brain that promote sleep. Caffeine absorbs rapidly into the bloodstream and reaches peak levels within 30-70 minutes. Its effects can then last 3 to 7 hours, but it may take up to 24 hours to fully eliminate this substance from the body.

Important Things to Know About Caffeine and Sleep

  • Makes it hard to fall asleep and stay asleep. 
  • Some people are more sensitive to the effects on sleep quality than others
  • If you are sensitive to or have sleep difficulties use caffeine cautiously
  • As a general rule avoid caffeinated drinks close to bedtime, and if you are sensitive you may need to avoid them altogether after lunch.
  • It can stay in your system for up to 24 hours
  • The amount of caffeine varies widely across different food and drinks
  • Understanding and controlling your intake and use is important for good quality sleep

There are different views on how many hours before bed you should have your last cup. Some say caffeine should be avoided for at least 3 to 7 hours before going to sleep. Others say no caffeine after lunchtime if you have sleep problems. Many people find that their sleep improves with less caffeine or only having caffeine earlier in the day.

Impact on sleep

Sleep disruptions caused by caffeinated food and drinks can vary between individuals due to people having different sensitivity levels. Older people may be more sensitive to its effects, while genetics may also contribute.

The body metabolises the substance more rapidly in people using nicotine (e.g., smoking cigarettes), but this process can be slower among pregnant women and women taking oral contraceptives.

Intake and effects

Moderate single doses of up to 200mg and a daily intake of less than 400mg do not seem to have negative health effects in healthy adults. This might be around 5 cups of regular strength black tea or 2 cups of brewed coffee (not too strong) per day.

When taken in low to moderate doses, positive effects can include alertness, mild euphoria and better cognitive performance (e.g. concentration, problem-solving). In higher doses, however, may result in stomach upset, feelings of jitteriness and trembling, and sleep disruption.

You may become dependent on caffeine if taken regularly. This means that if you stop suddenly having caffeinated food and drinks, you may have headaches, tiredness and anxiety. Gradually cutting down on it is better.

Caffeine to beat sleepiness

Because caffeine increases alertness it is commonly used to combat sleepiness during the day. Frequent, low-doses of it can help you stay alert if you are prone to sleepiness. This may be one cup of tea, soft drink or half a cup of instant coffee every 1-2 hours.

Although it may help beat sleepiness, this effect is only temporary and does not replace the benefits of a good night’s sleep.

Caffeine and sleep disorders

Sleep apnea is a common sleep disorder, but it can often go undiagnosed and untreated. A major symptom of this sleep disorder is high levels of daytime sleepiness [Obstructive Sleep Apnea (OSA)]. Given that caffeine helps alertness, some people with sleep apnea may use caffeine to mask their sleepiness. This may result in a delay in getting diagnosed and treated, which is not good for their health and wellbeing. Recent evidence of this link between untreated sleep apnea and increased caffeine use has been demonstrated, but further research is needed.

Cutting down on caffeinated goods is often advised to those with Restless Legs Syndrome and insomnia.

[Article sourced from the Sleep Health Foundation]

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