Chapter 3 - Sleep

Learning Outcomes

After reading through this chapter, you should be able to:

  • Describe the general functions of sleep.
  • Explain the consequences of sleep deprivation.
  • Explain ways of establishing a sleeping environment that can promote your sleep.

What is sleep?

Sleep is defined as a state of partial or full unconsciousness during which voluntary functions are suspended and the body rests and restores itself.

Despite the obvious importance of sleep, its specific function is not fully understood. In a broad sense, it is thought that during sleep the mind and the body “recover” from the stresses of the day and “prepare” for those to come. Information about the function of sleep has mainly come from studies depriving animals and humans of sleep.

Prolonged sleep deprivation of animals over two to three weeks resulted in skin lesions, weight loss, and ultimately death. In humans, prolonged sleep deprivation leads to reduced mental and physical performance and symptoms such as hand tremors, slurred speech, and increased sensitivity to pain.

Both the quality and quantity of sleep are determined largely by the timing of sleep in the 24-hour day. Human beings are programmed to sleep during the night and to be active during the day.

Sleep cycles and sleep structure

Sleep varies through the night; it is not uniform. The various sleep stages follow each other in a continuous cycle that lasts between 90 and 120 minutes. Each cycle is composed of five sleep stages. Stage 1 is where we fall asleep. During this stage, you may occasionally experience muscle twitches or starts. Stage 2 is a light sleep stage, when you are easily awakened. Stages 3 and 4 are deep sleep stages. These stages are considered to be those where the body regenerates. People are difficult to waken during these stages. The final stage is known as REM sleep, for rapid eye movement. If you were to observe a person in this stage of sleep, you would notice their eyes moving under their eyelids, and possibly some muscle twitches. This is the stage of sleep when we dream. This stage of sleep is important in learning and in memory consolidation.

Early in the night, we spend more time in stages 3 and 4 of each sleep cycle. As the night progresses, we spend more time in REM sleep. Whenever we are sleep deprived, our body will try first to catch up on deep sleep (stages 3 and 4) and REM. A person who is sleep-deprived will quickly fall asleep, and move rapidly from light sleep (stages 1 and 2) to deep slumber (stages 3 and 4).

The human sleep cycle , 90-120 min.: Stage 1, Stage 2, Stage 3, Stage 4, Stage 2, REM Sleep.  This image adapted from Shifting to Wellness, Keyano College, 1995.

The human sleep cycle


Can you recall any situations where you have suffered from sleep deprivation? Please provide details.


Recovery sleep

Unwanted sleepiness and fatigue can be considered an annoyance – and a danger under certain circumstances. It can be fatal, for instance, while driving a vehicle or flying an aircraft.

Many strategies have been identified to reduce the likelihood or consequences of fatigue. Some are discussed later in this workbook, such as the use of caffeine or being more aware of what you eat. More extreme examples include the use of amphetamines and other stimulants. However, such strategies are only a temporary fix, no matter how effective they are. At some stage, sleep must be obtained for physical and mental recovery to occur.

The exact amount of sleep that each person needs every 24 hours to perform optimally differs, but in general it’s between 7 and 9 hours. The need for sleep does not diminish as we get older, even though sleep may prove more difficult to obtain. Most people go to sleep naturally between 10 p.m. and 8 a.m. Older people tend to go to sleep earlier than younger people. Sleep is most valuable if obtained in a single block. However split sleep, or a number of short sleeps, is better than not getting any at all. A short sleep or nap can provide a powerful boost to alertness. However, it is important to know that napping does not eliminate the need for sleep. There are other considerations relating to napping covered in Chapter 4.


Approximately how many hours of sleep do you get (on average) per day?


Is this enough and do you think your performance would improve if you got more sleep per day?


Does the amount of sleep that you normally get vary with the different shifts that you work? If so, please explain.


Age and sleep

As we get older it becomes physically more difficult to stay asleep during a sleep period without waking up. This is particularly true during daytime sleep, but even nighttime sleep may prove to be more difficult as we get older. Falling asleep and poor sleep are not the only age-related changes that make non-traditional hours of work difficult. Recent research suggests that an aging bladder can contribute to sleep disturbances because it causes you to wake up more often to visit the toilet. Along with other age-related changes, this can cause more frequent awakenings across the sleep period. Frequent awakenings can lead to increased sleepiness when you are awake.


Have you noticed any significant changes in sleep patterns, either in yourself or in an acquaintance, that appear to be related to age? If so, what are they?


Setting up your bedroom

Obtaining adequate sleep can sometimes be a challenge, even in the most ideal circumstances. From both a biological and social perspective, sleeping during the day can cause the greatest difficulty. This is related to the body’s biological programming to be awake during the day, as well as the fact that it is noisier and brighter during the day. In addition, you may have more pressures on your time during the day. While some of these things are hard to change, you can set up your bedroom to maximize your chances of getting sleep when you have the opportunity.

Things you can do to your bedroom include:

  • Block out as much light as possible. This might involve the use of blackout curtains, roller shutters, heavy blinds, or even an inexpensive option such as black plastic.
  • Use your bedroom only for sleep, relaxation, and sex. Remove work desks, home offices, computers, and even televisions.
  • Control the noise that enters your bedroom. This can be done using physical barriers such as roller shutters, double glazed windows, and insulation, but it can also be managed by simply placing a sign on the door when you are sleeping. Unless you are on call, you should also turn down the telephone so that it does not disturb your sleep.
  • Reduce the disruptive noise that enters your bedroom. In addition to the physical barriers listed above, there are other ways that noise can be dampened out. For example, many people have success using a white noise source such as a fan, air conditioner, or relaxing CD on “repeat.” Ear plugs can be of use if you can sleep with them in. They are especially useful if you are sleeping away from home. Many workplaces supply foam ear plugs, and you can buy more solid siliconebased plugs at a drugstore or sporting goods store.
  • Minimize caffeine and alcohol intake in the hours before bedtime. Caffeine acts as a stimulant to keep you more awake. The stimulating effects of caffeine can last up to six hours. In addition, both caffeine and alcohol are diuretics, substances that flush water from your body. That is, they make you more likely to wake up to go to the toilet.
  • Set up a “thermo-neutral” zone. The body sleeps best when the environmental temperature is between 18 and 24°C. If you are too cold or too hot, your body will wake up to control its temperature more efficiently. A thermo -neutral zone is best set up using good placement of the bedroom in the house, good use of insulation, and using an air conditioner or heater with a thermostat.
  • Don’t panic if you can’t get to sleep. Most people have days when they can’t sleep. Staying in bed, trying your hardest to get to sleep is unlikely to help, and may even make sleep more difficult. If you cannot sleep within 30 minutes, get out of bed and do something relaxing instead of staying in bed and being frustrated with yourself.
  • Establish a pre-bed routine, including quiet/relaxing activities. Each bedtime, do the same activities in the same order. For example, shower, clean your teeth, and lock the door. It doesn’t matter how many things you do, so long as they are always the same and in the same order each time. This trains your body to associate these activities with falling asleep.
  • Consult with your doctor if you suspect – or have been told – that you have a sleep disorder. Signs like making choking sounds or stopping breathing regularly during your sleep are classic symptoms of sleep apnea, a breathing-related sleep disorder that can reduce your capacity to stay awake when you are at work, driving, or engaged in other activities.


Are there any improvements you could make to the way your bedroom is set up? What are they?



Insomnia generally refers to difficulty falling asleep or staying asleep. A frequent medical complaint, it is the most common type of sleep problem. Rates of insomnia are higher in shift workers and people who work non-traditional hours.

Insomnia is usually defined as being transient (lasting up to one week), short-term (lasting weeks to months), or chronic (lasting longer than three months).

Treatments focus on chronic insomnia because most people experience transient or short-term insomnias several times a year.

There are many potential contributors to insomnia. These include work hours, life stressors, age, and sleep environment. Treatments may involve changes to schedules, habits, and lifestyle. The use of drug treatments is controversial and is most useful for transient or short-term insomnia.

Case study

Man in bedDamien is 51, married and has three grown children. He has spent 18 years working shifts as an aircraft maintenance engineer. He drives 45 minutes each way to work his 12-hour shifts.

Recently, Damien drove off the road on his way home from work at 5:45 a.m. Although it’s normal to be tired after working a night shift, it was the fourth time in the past six months and this time it scared him. He stopped the vehicle, and walked around outside in the cold air before he continued home.

Although he has been avoiding talking to his doctor about a possible sleep disorder, this latest incident was the trigger for Damien to make an appointment. His wife, Tonia, has been telling him for nearly two years to do something because his stories about nearly falling asleep at work or on the way home from work scared her. Damien thought he could avoid an accident, but now realizes that he could hurt himself or others if he does not get help.


checkmark Knowledge Check

  • How could Damien improve his sleep?
  • Who should Damien see regarding his sleeping problem?
  • On average how many hours of sleep should you ideally get each night? How can “white” noise positively affect sleep?
  • What room temperature range is most suitable for promoting sleep?
  • Explain the positive effect of a pre-bedtime routine.
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