Understanding the Side Effects of Sleeping Pills

Apr 02, 2014
Risks of sleeping medications, falls, addition, car accidents.

Are Z Drugs Safe?

Over the past few years increasing evidence is emerging about the side effects and risks of the Z drugs. The two on the market in Canada include Zopiclone (Imovane®) and Zolpidem (Sublinox® in Canada, Ambien® in the US). Zopiclone has been on the market for many years. It is available as a generic and is covered by all drug benefit plans. Zolpidem has come to Canada more recently and is not yet covered by Alberta Blue Cross (which covers many government workers and people on AISH and other Alberta Government benefit plans).

Each drug has benefits and risks and these vary depending on individual variation. The information below will help you identify which risks you may be facing if you are taking medications to sleep. Please note I am not publishing this to scare everyone off the drugs. They have their place. However, you deserve to be fully informed so you can decide which risks you are willing to take. 

Possible Side Effects and Risks of Z Drugs

  • Risk of Addiction/abuse 
  • Risk of Falling
  • Risk of Driving Accidents

Risk of Addiction/abuse with Sleeping Medications: Which Have Highest Risk?

A post-marketing study of relative abuse liability of hypnotic sedative drugs by Jerome H. Jaffe and colleagues Addiction, 99, 165–173

The first common worry about drugs used to help people sleep is that of addiction. Addiction is defined as using the drug for something other than its intended use eg. using a drug to get "high" rather than to sleep and to obtaining the drug through illegal means to keep up the habit. Jerome Jaffe and colleagues conducted a study of patients in treatment for drug abuse. They asked these people with obvious addiction tendencies their history of using (for sleep) and abusing (to get high) the common medications used for sleep including the tricyclic antidepressants (eg. amitriptyline), trazodone ( a weak antidepressant which is now the most commonly used sleep medication in the US), the benzodiazepines (such as alprazolam) and the Z-drugs zopiclone and zolpidem. They found that the benzodiazepines had a high rate of addiction (10 – 14% of those using the drug). The tricyclic antidepressants and zolpidem similar low rates between 1 – 2%. Zopiclone had an addiction rate of 5%.  Trazodone and antihistamines had the lowest rate of addiction among drug addicts at less than 1%.

In this sample, few subjects had used either trazodone or zolpidem so the rates may be underestimates. Also the rate of becoming addicted to a drug is lower in people who have not history of addiction that those with a history. This means that those who have been addicted to drugs or alcohol in the past will be at higher risk than the average patient.

Risk of Falling With Sleeping Medications

Risk of Falling and Hypnotic Drugs: Retrospective Study of Inpatients. Kyoko Obayashi Drugs R D (2013) 13:159–164.

Another risk of any sedating medication is the risk of falling. This is especially true if the medication lasts for several hours and the person wakes in the middle of the night to use the toilet. This study looked at the rates of falling in hospitals in patients who were taking medications for sleep. The rates of falls in people taking medication are compared to the rate of falls in those on no medication. The rate of falls in people taking zopiclone is similar to that of people taking benzodiazepines. The rate in zolpidem is much lower. The reason for this is likely the short duration of time it spends in the body. This is a benefit with regards to falls but may be a problem for those who need a longer-acting drug to stay asleep. The rate of falls with drugs uses for seizures, Parkinson's Disease and with opiate pain killers is even higher.

The average age of these patients was 58 – older people are more likely to be admitted to the hospital and to be taking medications. And also remember that if you are on more than one sedating drug your risk will be higher, possibly much higher. Also if your brain is already struggling to work at optimal capacity because of your illness, the effects of medications may be increased. For example, some patients with ME/CFS and FM have poor balance due to the illness. Sedating medications may make balance even worse. And with age, the brain becomes more vulnerable to both the beneficial and unwanted effects of drugs. For all these reasons it is important to be on the lowest dose of sleeping and other medications necessary to maintain quality of life.

Risk of Driving Accidents With Sleeping Medications

Hypnotics and Driving Safety: Meta-Analyses of Randomized Controlled

Trials Applying the on-the-Road Driving Test Joris C. Verster*,Current Drug Safety, 2006, 1, 63-71

In this study, subjects were given a sleep medication: 10 – 11 hours before waking (the usual way to use sleep meds), a double dose at bedtime (common in people for whom one dose doesn't work) and 4 – 6 hours before waking (common in ME/CFS and FM in which people often take a "split dose" when they wake up in the night. The participants were taken on a driving test in a car with a camera mounted on the roof that measured how well the driver maintains the car in the middle of the lane. Increased lateral movement (swerving) is a measure of likelihood of getting in an accident. The study statistically integrates data from 10 previous studies and comes up with the "average" result. The results for each drug are reported in "effect sizes" which compares the effect in participants who took a given drug with those who were drug-free or took a different drug. The effects are rated as small, medium or large.

The authors conclude that commonly used sleep medications may be a contributor to traffic accidents. 

They recommend zolpidem as the safest alternative. Women are likely to be more affected than men as they have a smaller body volume in which the drug is diluted.

What drug causes the most car accidents?

Drug Type

Rate of addiction among known addicts

Rate of Falls

Effect on Driving


(eg. lorazepam)


1 – 4 X

Large effect taken at night either usual or double dose. Still large if driving the next afternoon.



(eg. amitriptyline)

1 – 2%










Large effect if taken at bedtime or in the night. No effect for driving the next afternoon.



< 1X

No effect if taken either at bedtime. Large effect if taken in the night. No effect if driving the next afternoon.

If space is blank it is because the drug was not reported in the given study

All sedating drugs decrease alertness. Drugs such as antidepressants which are used for sleep because they last longer in the body have not been studied but may impact falls and driving risk well into the day.

None of the studies have a comparison group of participants who have insomnia and non-restorative sleep but don't use any medication. It may be that lack of sleep also places people at risk for falls and driving accidents. The studies also do not measure the quality of life reported with and without the medications. However, a fall or bad traffic accident can seriously and quickly diminish the quality of life!

How to get to sleep naturally.

Every person should make an informed choice when deciding whether to use a sleep medication and this information is to assist you with this. Using non-drug strategies such as improving sleep hygiene, stress management or meditation/breathing/self-hypnosis may be lower risk options than using any medication on a regular basis.

For more help see my recently published book More Light. In new Chapter 4: sleep for my new book and we are about to release a single session online education module on sleep.

Author: Eleanor (Ellie) Stein MD FRCP(C)

I am a psychiatrist with a small private practice in Calgary and am an assistant clinical professor in the faculty of medicine at the University of Calgary. Since 2000, I have worked with over 1000 patients, all with ME/CFS, FM and ES. My passion for this field comes from my own struggle with these diseases, my desire to improve my health and then pass on what I learn. My goal is for every patient in Canada to have access to respectful, effective health care within the publicly funded system. 


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