Focus On: Sleep
Sleep & Circadian Rhythms
Sleep is complex. It is dictated by our internal clock called a circadian rhythm. Our flow of energy is biologically determined but generally coincides with daylight and dark over about a 25 hour period. Think of the brain as a battery, charging during sleep and discharging during the day.
Sleep occurs in 5 cycles of approximately 90-110 minutes.
- Stage 1 - very light sleep (we can be easily awakened)
- Stage 2 - eye and brain movements have slowed
- Stage 3 & 4 - deep sleep (slow brain waves appear and dominate brain activity)
- Stage 5 - REM sleep
At the end of the 2 nd cycle, Rapid Eye Movement (REM) sleep happens. This is when we dream. Our heart rate increases and blood pressure rises. We may have periodic muscle twitches, pupil dilation and increased respiratory rate. REM sleep represents 20-25% of total sleep time. During non-REM sleep, hormones are released which help the body rebuild itself from the activities of the day.
Most adults need 7-9 hours of sleep each day..
One poor sleep can reduce memory, attention, coordination and response time the next day. Many things can affect our ability to get a good sleep:
- caring for very young children or other dependent family members
- feelings of stress
- excessive intake of alcohol, caffeine and/or smoking cigarettes
- medical conditions that affect breathing (e.g. heart disease, asthma, allergies, Chronic Obstructive Pulmonary Disease) or are painful (e.g. cancer, arthritis)
- shiftwork or erratic work schedules
Common Sleep Disorders
Fatigue can have a number of causes. When your feelings of tiredness start to affect your awake time functioning, it may be time to seek professional help.
In Canada , the most common sleep disorders include:
- Insomnia is trouble falling asleep, or waking up frequently during the night or early morning.
- Sleep Apnea occurs when the airway becomes temporarily blocked and is characterized by loud snoring. Unsure if your snoring is something to be concerned about? Take the Canadian Lung Association’s sleep apnea sleepiness test.
- Restless leg syndrome is a strong feeling of “pins and needles” in the legs and feet that prevents or disrupts sleep.
Shiftwork and Sleep
Getting quality daytime sleep is a challenge. Absenteeism, work injuries and accidents (PDF 1MB, 24 pages) all increase with a tired workforce. Driving while drowsy has been linked to aggressive driving and automobile collisions.
At work, carpooling and napping rooms can reduce the occurrence of “drowsy driving”. An Orientation to Shiftwork Program (PDF, 2 pages) can highlight the common health effects and “bad habits” workers can develop, and can provide solutions on how to deal with sleep problems and other shift work issues. Employers should look at other environmental factors in the workplace to reduce the sleepiness of workers.
At home, create sleeping “rules” with family and friends to maximize your sleeping time. See the Shiftwork Handbook link in our resource section for ideas.
The Cost of Tired Workers
The cost of sleep disorders in Canada is based on American statistics. American estimates place the direct costs at 15.9 billion annually and go up to $100 billion dollars in indirect losses for sleep deprivation in that country. In Canada , this would translate into $1.6 billion in direct costs and another $5-10 billion dollars in related costs.
In the United States , each year drowsy driving related crashes cost 12.5 billion dollars nationally.
8 Tips for Improving Your Sleep
- Make sleep a priority.
- Don’t disturb your circadian rhythm. Go to bed and get up at the same time everyday even on weekends and vacations.
- Exercise. Regular exercise is known to improve sleeping habits, however, do not exercise too close to bedtime as it may then be difficult to fall asleep.
- Don’t lie in bed awake. If you cannot fall asleep or get back to sleep, get up and do something that will help you relax until you feel sleepy again.
- Limit Alcohol, Nicotine and Caffeine. Nicotine and caffeine are stimulants that take many hours to be eliminated from the body.
- Don’t eat/drink then go to bed. Eating and/or drinkingtoo close to bedtime can prevent a restful sleep. Try to avoid both for at least a few hours before going to bed.
- Make your bedroom comfortable. Make sure the room is dark and quiet and the temperature of the room is comfortable. Think about setting limits on children and pets sleeping with you. Save your bedroom only for sleeping and sex.
- Improve air quality. Airborne allergens call trigger allergies and asthma which then affect sleep. The Lung Association has some tips for a Healthy Home.
Facts and Stats
- Adults 32-59 years old that routinely sleep 5 hours or less are 50% more likely to develop hypertension than those who sleep 7-8 hours per night (Gangwisch et al, 2006).
- Adults that had 4 hrs of sleep per night for two weeks had reduced judgement and performance and matched those that had not slept for 88hrs (Dinges, D. et al, 2003).
- In adults, sleep of 8-8.4 hours is considered fully restorative.
- Research has found a relationship between sleep and appetite (Taheri et. al., 2004).
Credit Valley Hospital Sleep Lab (905-813-2712) is part of the cardiopulmonary unit specializing in diagnosis and treatment of sleep disorders. Referral is through a family doctor. Currently there is an average of 2 month waitlist for an appointment.