How medications can impact your body clock and sleep.

By Lydia Hales.

It’s no secret a coffee too close to bedtime — or even a cup tea for some — can make it hard to get to sleep.

Drugs like the caffeine in your cappuccino and other stimulants like those found in cold and flu pills are widely known for their effect on sleep.

But there’s a range of other drugs that can impact sleep in ways you might not be aware of.

According to David Ray, Professor of Medicine and Endocrinology at the University of Manchester, there is still much for the experts to learn when it comes to the science of how medications interact with sleep.

Dr Ray believes the delivery of many medicines will one day be tailored to the timing of an individual’s body clock, in a bid to get the most from specific drugs.

Because everyone’s preferred sleep cycle (also known as your chronotype) varies by age, gender, and genetics, a person’s “internal time” does not necessarily match the clock on the wall.


So as researchers gain a better understanding of how different drugs interact with body clocks, personalising treatment in the future might couple internal time-keeping with a smart-release mechanism for drug delivery, Dr Ray said.

Symptoms that present during sleeping hours, such as nocturnal asthma, could be good targets for specifically timed drug release, he said.

Despite this, it’s a concept that is already applied, to a certain extent, in current medical practise — for example with some varieties of statins, a class of drug widely used to reduce cholesterol in the blood.

“The early generation of statins had quite a short half-life, and they essentially only work if you give them at night,” Dr Ray said.

“So if you give them in the morning they have no effect, because the enzyme they inhibit is only really active overnight.”

The half-life of a drug is the time it takes for it to halve in concentration in your body, and drugs with short half-lives are typically those that need to be taken multiple times a day.

Your body clock affects the levels of different hormones in your body throughout the day and night, to prepare for different activities. For example in the morning, it ramps up the level of the steroid hormone cortisol, to help you get up and tackle the day.

What this all means it that sometimes, matching a drug’s half-life and the time of day it is taken with these fluctuations in hormone levels, can be used to provide more effective treatments.

So which drugs interact with our body clock?

“Essentially … many of the drugs we use will interact with the circadian clock,” Dr Ray said.

But that’s not a good reason to stop, or make changes to the medications you’re currently taking without talking to your doctor, he said.

From studies in animals like mice, we now understand some of the basic mechanisms involved in body clocks.

And Dr Ray says scientists in the field are now beginning to translate this research into the clinic. The aim is to see how these processes work in humans, and how they could be used to make current drugs more effective.

“For some drugs, such as the statins, it’s clear and we already know that the time of day makes a big difference to how they work,” Dr Ray said.

“For others such as glucocorticoids, we know that the time of day may impact the drug’s side effects — for example disrupting sleep.”

Glucocorticoids are a type of steroid drug widely used for treating inflammation.

“In the UK more than 1 per cent of the population have a regular, repeat prescription for a glucocorticoid — we know that those drugs directly regulate the clock, and patients who are given them to take in the evening very frequently describe disturbed sleep,” Dr Ray said.

“So often people will say ‘oh I’ll take it in the morning’, but … we don’t really know beyond these anecdotes … what the consequences are of taking it at different times of day, either for it to be the most effective or to get the best window between the beneficial effects and the off-target effects.”

Despite not knowing the effect that taking them at different times of day might have, they’re still very effective medications, Dr Ray said.

He’s currently doing research into the time of day that patients with a long-term steroid prescription take their medication, to see if there are any associated side-effect risks.

What about sleeping pills?

Melatonin, a hormone that normally increases in your body at night-time to help you prepare for sleep, is available in prescription-only pills in Australia. It’s most-often promoted to help insomnia, or to reset an out-of-synch body clock due to jet lag or sleep disorders.

But the appropriateness, timing and dosage need to be considered for each specific sleep problem, and the research into the effectiveness of melatonin tablets is ongoing.

According to Dr Ray, “the dose of melatonin in most [Australian] tablets is too low to achieve a meaningful increase in concentration in the brain, where it has its action preparing the brain for sleep.”

Night time cold and flu medications are another go-to for people who are looking to get more sleep. The culprits in these tablets, as in many over-the-counter sleeping pills, are drugs known as “older generation” or sedating antihistamines, which include diphenhydramine and doxylamine succinate.

While they can encourage sleep, the quality isn’t the same—and they won’t help shift your sleep cycle, since they don’t affect the body clock. You’d be better off making changes to your behaviour to improve your sleep, Dr Ray said.

The future of sleep disorder treatments

Scientists are also beginning to identify chemicals that could be used to affect the clock in a specific way, for example to treat people with sleep disorders.

In 2014 researchers at the Salk Institute discovered that a single gene keeps the cells of the body’s master clock in synch, and that reducing its activity allowed cells to adjust to a light-dark shift more quickly.

Scientists believe drugs that specifically alter the body clock could provide a potential cure for jetlag.

They could also have much wider implications for sleep disorders and serious disease — as it’s thought that sleep disorders may increase the risk of developing dementia, and they often occur before periods of mental illness, including onsets of psychosis in people at risk of schizophrenia.

“We are in the very early stages of identifying molecules that can be used to affect the clock, but those are a few years off, and would be used primarily to treat primary disorders of the circadian rhythm, or of sleep,” Dr Ray said.

This post originally appeared on ABC News.

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