High Latitude Sleep under a Midnight Sun and Seasonal

Affective Disorder (SAD)

Implications for Function, Performance, and Well-Being

Gary Podolsky, M. D.

Objectives

1. Review current models of normal sleep

2. Discuss Healthy sleep hygiene practices

3. Discuss sleep disorders related to Seasonal Affective disorder in the Northern Latitudes

Sleep problems happen to visitors to the Canadian North, as they adjust to longer days or nights compared to more Southern daytime hours. During the summer months of a midnight sun adaptations to excessive daylight must occur to ensure sleep. Lack of daylight during the winter may also precipitate seasonal affective disorder in those susceptible.

Other factors such as cold, isolation, lack of physical exercise, and alcoholism also affect mood.

"There are two very common reasons for yawning and looking like hell in the Arctic. The first is the winter and the second is the summer"

NORMAL SLEEP CIRCADIAN RHYTHM

Humans have a free running 25-hour clock, which has to be constant. Other cycles exist that we often forget about. These include infradian, which are greater than daily such as the menstrual cycle. Ultradian cycles are less than once per day including pulse and respiratory rate.

Biological Rhythms are not biorhythms, which are a pseudo science.

Biorhythm is the practice of forecasting events by intellectual, physical, and emotional "cycles"

Sleep Has Several Definitions

"Sleep is a process of regulation of the metabolism and the temperal inter-relationships in activities of structure and functional systems. "Soviet Sleep Symposium 1982.A good working defintion:"A state of inertia and loss of consciousness of a temporal nature from which we are easily aroused"

SLEEP IN STAGES

Non REM sleep (Brain Idle, Body Mobile)

Stage one (Transitional Period)- usually happens within 10 min, unless a sleep disorder is present. Brain activity slows and eyes roll from side to side.

Many people awakened at this stage will claim they were not asleep. This may be similar to "automatic behavior" the routine doing of tasks while seemingly awake.

Stage two " somewhat deeper"

Eye movements halt. The brain will respond to levels of noise (shown on EEG)

Half of adult sleep is spent here.

Stage 2 usually lasts 20 minutes.

Stage 3 and 4 - Slow Wave Sleep (also called delta sleep)

Brain cells in the cortex fire slow large spikes. Stages 3 and 4 may be difficult to distinguish. Stage 4 is the deepest sleep. Most stage 4 occurs early in night. It is very difficult to awaken someone within one hour of sleep. Adolescents have 25% of their sleep here, which declines with age to become absent in the elderly. After sleep deprivation this sleep is made up first and is more important for physical recuperation. Growth hormone is secreted in stage 4.

If deprived of stage 4, people complain of fatigue and muscular soreness

 REM Sleep Brain on, Body off

First REM usually after 90-120 minutes of NREM sleep

•  Rapid Eye Movements

•  EEG similar to wakefulness

•  Increased oxygen consumption

•  Increased cerebral blood flow (more than when awake)

•  Irregular pulse. Respiration, and blood pressure

•  Isolated muscle twitches

•  Loss of facial muscle tone

•  Dreams

REM also gets longer as the night goes on. That is why most people are dreaming when the alarm goes off. Most sleep has 4-6 REM episodes. Infants spend 50% of time in REM.Age >5 25% of time, and this stays constant over a lifetime

Most REM occurs at the end of 7-8 hrs. Those who don't get enough sleep, or if it is fragmented, tend to be REM deprived.

Horne defines: The first 3-4 hours as core sleep (this contains the bulk of the nights total SWS). The remainder of sleep was considered "optional sleep".

Made up sleep is mostly stage 4 SWS and half of the missing REM

The sensation of sleepiness is a combination of: Physiological (missing core sleep) and psychological (missing optional sleep)

People tend to be sleepiest at 03:00 and another low at 14:00 (siesta time)

Siestas at 2 pm tend to produce better quality sleep than naps at other times because they are richer in REM

ALERTNESS

Motor vehicle accidents are 8 times greater between 24:00- 8:00 (peak at 03:00-06:00)-Lowest point of alertness. Yet there are less vehicles on road

German Study on Automatic behavior.

Showed automatic behavior in drivers, railroad, computer, and nursing workers.

Their EEG showed light sleeping pattern and no blinking.

When stimulation occurred person became awake but their was no anticipation of events- as if on autopilot.

Daytime Alertness Depends on:

•  Circadian phase

•  Total sleep the night before

•  Amount of SWS sleep

•  Regularity of sleep and work schedule

Performance can be correlated to 24h body temperature curves. People usually do best when their temperatures peak.

Morning People (Larks) - like to go to bed early and rise early. They have peak body temp before noon.

Evening Types (Owls) - like to get things done at night and sleep in. Have their body temperatures peak in 2 nd half of the day.

Post lunch Dip.

Fall in performance not accompanied by body temperature decrease. This does coincide with the siesta time (14:00).

SHIFT WORK HAS BEEN BONE THROUGHOUT HISTORY

Light bulb was invented in 1883, which made shift work economically feasible. Murderous shift work gave rise to unions. In the1920s, the average workweek decreased from 72.3 to 59.8 hrs. TheWolsh-Healey Act established standard work week at 40-42 hrs.

Shift Workers

•  20%-No trouble with changing shifts

•  60% Moderate Hardship

•  20% Extreme difficulty and abandon shift work within 1 year

•  Most people with no shift work problems are owls on standardized tests

•  Larks are more likely to have problems

•  Age> 40 have more difficulty

Shift Work Problems

Circadian disharmony- "jet lag" malaise one experiences until adaptation to a new shift occurs, which can last up to a week.

"Inappropriate phasing"- trying to stay awake while circadian clock says otherwise (isolated night shifts)

Research on insects and mammals forced to rotate sleep/wake cycles show up to 20% increased mortality.

Shift Worker Health

•  Increased accidents on job

•  Greater risk of fatal accidents

•  Increased accidents to and from work

•  8 times risk of stomach ulcers (compared with day shifts)

•  Increased depression

•  Increased mood changes

•  Higher rate of drug and alcohol abuse

•  Increased hypertension

•  Increased cardiovascular events (more so than smoking 1 pack per day)

•  Increased infertility in women

•  Increased divorce rate.

Traditional Shift Rotation ( Southern Swing, Dow Schedule, Hoover, Hanford)

Usually has been weekly counterclockwise rotation. This is destructive to the body

Reasons For Problems With Weekly Counter Clock Shift

1) Normal circadian cycle is 25hrs.

Always easier to delay sleeping than to advance it. Internal clock adjusts easily to 2 hours delay or 1-hour advance. This is similar to flying East to West, compared with West to East.

2) Shift workers on counterclockwise rotations take 1-2 weeks to reset their biological clocks. With a weekly change- they never adjust

3) Weekly shift changes are disruptive to family and social life.

Clockwise shift work is recommended with at least one-month period on long rotations to permit circadian rhythm stabilization. Many shift workers te nd to favor 12 hr shifts. Many industries rotate every week. It is harder to adjust with a 12 h shift compared to an 8.

Emergency medicine doctors tend to fatigue during the last few hours of a shift

The American College of Emergency Physicians reported that an 8hr shift is the most desirable.24 hr shift is sometimes practiced in ER. Very Insane. Need at least 304 house of quality uninterrupted core sleep in a year.

"French System" Clockwise rotation through all the shifts over consecutive 3 days. Working theory is that it is too difficult to reset the biological clock so get it over soon. This leads to circadian fatigue during the night shift. This method is rare but was used at the Grace Hospital.

GOLD STANDARD

Work the same shift all the time. If working a night shift workers must maintain the same sleep period every night to avoid disrupting the biological clock.

Daytime light is a powerful influence and exposure can make better or worse acclimation to night shifts. This is disrupted when individuals move to extreme latitude where daylight is dramatically increased or decreased.

ANCHOR SLEEP

Is a period of at least 4 hours during which one sleep while working on night shift rotation.

Example: Sleep from 800-1600 after working nights

Sleep 0400-1200 on days you don't work

Core sleep is time in common 800-1200

This anchors the circadian rhythm to a particular shift.

Isolated Night Shift

Work a night shift in addition to regular shifts (classic " on call"). This can work well for large groups but a problem when 1 in 4. Recent literature condemns weekly shift changes whether clockwise or counterclockwise.

Short stretches of night shifts allow split sleep periods

Since a very short run of night shifts will not be long enough to readjust the circadian clock it is better strategy to stay " dayside" than go to "night side" since for the individual who must return to day work should stay orientated to day. Workers are suggested to:

Sleep in 2 four hr shifts adjacent to your regular shift.

Sleep > 4 hrs can significantly affect the next night sleep

Sleep hygiene

Awakenings lead to a decreased proportion of stage 1 sleep.

Solutions: Earplugs, soundproofing and adding white noise device.

Temperature: Ideal temperature unknown.

T> 24 degrees C disturbs sleep, T< 22 degrees C causes emotional and unpleasant dreams

Weather - very high and very low barometric pressures induce sleepiness.

Mattress- surface unimportant for sleep but does make differences for orthopedic purposes.

Light In the North unwanted light can be blocked with drop down drapes. If unavailable the poor man's solution is to place tinfoil at the window.

SLEEP HYGIENE

Avoid caffeine and other methyl xanthines, and avoid alcohol at bedtime. Regarding diet- Milk products may help. Regularity of eating time helps

Suggestions For Use Of Bedroom

•  Use for sleep or sex

•  Avoid work, worry, or exercise just before sleep.

•  Sleep behavior- everyone has a ritual. Whatever it is keep it regular

•  If no sleep after 30 min get out of bed and do some sleep inducing activity (read, watch TV)

NAPPING-CONTROVERSIAL

•  After a night shift a nap is generally thought to be good.

•  Napping before a night shift may be subjectively good. (No evidence of harm)

•  Should plan at least 20 min extra time after before awakening before starting work, to avoid sleep inertia.

•  Power naps 45-60 min may be helpful

•  Naps greater than 2 hrs can interfere with the next nights sleep

BRIGHT LIGHT EXPOSURE

This shifts the peak temperature and changes the pattern of cortisone release.

Improved function in sleep deprived when exposed to 1000-lux ambient light when compared with 1-20, and 100 lux.

Before sleep avoid bright light

After a daytime sleep spend 1-2 hours in bright light.

Alcohol May make one drowsy but cause poor sleep, and it decreases REM. Chronic Alcoholics may experience 100% REM during withdrawal. Delirium tremens may represent breakthrough REM. Alcohol also causes more sleep fragmentation, partially due to nocturia.

Caffeine and Nicotine stimulants and should be avoided 4 hours before sleep.

Sleeping Pills. There are no miracle drugs.

Halcyon (triazolam) once thought to be great but dependence.

Some advocate diphenylhydramine as best sleep pill for shift workers.

Starnoc 5-10mg also has a very short half-light. It has wash out in 4 hrs. One still has to be very careful prescribing this.

Melatonin

•  No adverse side effects

•  Improved sleep architecture

•  More growth hormone secretion

•  Boosts immune response

•  Effective in promoting sleep

•  Cheap (available US)

•  Not available in Canada. May bring in for personal use.

Sleep Strategies

•  Social Life- Important to integrate this for shift workers

•  Physical activity- helps promote wakefulness.

•  Environment- interaction with regular daylight. May use artificial light boxes as used for seasonal affective disorder (see below)

•  Drugs-use caffeine strategically i.e. Help with 0200-0500 troughs in wakefulness.

•  Japanese catnap: Schedule a nap in the middle of a nighttime shift for 45-60 minutes in a quiet area. This might correspond to the night shift lunch hour.

CONCLUSIONS FOR SHIFT WORKERS

•  Shorter shifts are better.

•  Isolated nights shift are possibly acceptable with minimal drawbacks.

•  Shifts should be rotated clockwise with one-month minimum stability before change.

•  Sleep in a darkened room. Consider using melatonin.

•  When no choice, anchor sleep or catnips can minimize disruptions in sleep.

•  Avoid caffeine and high calorie junk food at night.

•  Bright light helps 10,000 lux for 2hrs after rising

•  Get regular exercise. Vigorous exercise after rising helps.

•  Regular exercise in the afternoon or early evening helps promote sleep.

•  Avoid heavy exercise prior to sleep.

•  Work with friends and family and plan quality time together.

•  Don't live two lives.

•  Don't live a day shift life while working a night shift schedule.

SEASONAL AFFECTIVE DISORDER

SAD (Seasonal Affective Disorder) is a type of winter depression that affects an estimated half a million people every winter between September and April, in particular during December, January and February.

It is caused by a biochemical imbalance in the hypothalamus due to the shortening of daylight hours and the lack of sunlight in winter. For many people SAD is a seriously disabling illness, preventing them from functioning normally without continuous medical treatment. For others, it is a mild but debilitating condition causing discomfort but not severe suffering. We call this subsyndromal SAD or 'winter blues.

EPIDEMIOLOGY OF SAD

About 70-80% of those with SAD are women. The most common age of onset is in one's thirties, but cases of childhood SAD have been reported and successfully treated. For every individual with full blown SAD, there are many more with milder "Winter Blues." The incidence of SAD increases with increasing latitude up to a point, but does not continue increasing all the way to the poles. There seems to be interplay between an individual's innate vulnerability and her degree of light exposure.

THEORIES ABOUT HOW LIGHT AFFECTS MOOD AND SLEEP

In 1984, a psychiatrist at NIMH, Norman Rosenthal, published a paper on the use of bright light therapy in patients with this disorder. Since then, well-designed studies have confirmed these findings. Researchers are still investigating mode by which bright light can lift depression or reset a sleep cycle. One theory is that the suprachiasmatic nucleus, near the visual pathway, responds to light by sending out a signal to suppress the secretion of a hormone called melatonin. Brain studies suggest that there is impairment serotonin function in neurons leading to the suprachiasmatic nucleus.

Initial theories suggested a pathway from the retina to the suprachiasmatic nucleus. However some recent research indicated that bright light applied to the back of an individual's knee could shift human circadian rhythms. This suggests that the bloodstream, not just the neurons of the visual pathways, might mediate the biological clock.

Treatment of SAD Light therapy has been shown to be effective in up to 85 per cent of diagnosed cases. That is, exposure, for up to four hours per day (average 1-2 hours) to very bright light, at least ten times the intensity of ordinary domestic lighting .

Ordinary light bulbs and fittings are not strong enough. Average domestic or office lighting emits an intensity of 200-500 lux but the minimum dose, necessary to treat SAD is 2500 lux, the intensity of a bright summer day can be 100,000 lux!

Light treatment should be used daily in Winter (and in dull periods in summer) starting in early Autumn when the first symptoms appear. It consists of sitting two to three feet away from a specially designed light box, usually on a table, allowing the light to shine directly through the eyes. The user can carry out normal activity such as reading, working, eating and knitting while stationary in front of the box. It is not necessary to stare at the light although this has been to be proved safe.

Treatment is usually effective within three or four days and the effect continues provided it is used every day. Tinted lenses, or any device that blocks the light to the retina of the eye, should not be worn,

Some light boxes emit higher intensity of light, up to 10,000 lux, which can cut treatment time down to half an hour a day.

How to use a light box : Light boxes are available from a number of manufacturers. Some individuals who use a 10,000-lux box may only need 30 minutes of daily light treatment. However, the amount of light needed varies widely from individual to individual.

The light treatment is most often done in the morning, but studies have suggested that either morning or evening light can help SAD. Some people may get insomnia when they use the light in the evening. Initially, researchers felt that one needed full spectrum light. Now, studies suggest that regular fluorescent lights will work as well. UV (ultraviolet) light can damage eyes and skin, so it must be filtered out.

It is best to buy a commercially built light box to be sure of the exact amount of light and to be sure that there are no isolated "hot spots" which could damage eyes. Many people still prefer full spectrum (minus UV) light because it is closest to natural lighting. The individual measures the distance from her face to the light source. This measurement is important, and should be repeated daily for several days and occasionally after that. The light needs to strike one's eyes, but one does not need to look directly into the light source. It is fine to occasionally glance directly into the light. Many people read a book or eat breakfast while using the lights. Sitting still for 30 minutes to several hours is not an option for some people. For these people, the light visor is an option. Others are able to take one of the compact light boxes to work and use it for several hours. It is best to use the light source in an uninterrupted time block, but it can be helpful even with some interruptions.

Long-term treatment compliance is often more difficult than one might initially anticipate. This is an important reason to have professional monitoring. Having to account for your regular use (or the lack thereof) is a powerful motivator. It is also helpful to have an outside objective individual to help monitor your response to the treatment.

Since one of the symptoms of SAD can be difficulty awakening in the morning, some find it helpful to have the light turn on just before they are supposed to wake up. Some individuals like to use a Dawn Simulator. This is a bright light that is programmed to gradually increase its intensity such that it reaches its full intensity a set period before the individual is scheduled to awaken. Although it is less gentle, some people will put their light box beside their bed and hook it up to a timer set to turn on shortly before awakening.

Some people like to use full spectrum light bulbs for everyday household use. There is no evidence that these low intensity bulbs affect mood or sleep phase. Your plant light will not cure your SAD. Your 10,000-lux light however, may be nice for some of your plants.

OTHER TREATMENTS

Outdoor light, even when the sky is overcast, provides as much or more light than a light box. There has been a study showing improvement in SAD symptoms when individuals took a one-hour daily walk outside. Outside light is often brighter than the light boxes. Spending an hour outside each day can often produce beneficial results in some individuals. However, one cannot get early morning outside light in the winter. Not everyone's job will allow for an hour-long outside walk. Only highly motivated people will continue their daily walk when it rains or snows.

Antidepressant drugs    Traditional antidepressant drugs such as tricyclics are not usually helpful for SAD as they exacerbate the sleepiness and lethargy that are symptoms of the illness. The non-sedative SSRI drugs such as fluoxetine (Prozac) are effective in alleviating the depressive symptoms of SAD and combine well with light therapy.

Psychotherapy Counselling or any complementary therapy, which helps the sufferer to relax, accept their illness and cope with its limitations are extremely useful. Since SAD may be considered a psychiatric illness a qualified practitioner such as a psychiatrist, family physician or psychologist familiar with SAD and other mental illnesses such as addiction, bipolar disorders and others, which may mask as SAD, should follow this. Using light, as a "medication" may be benign but the patients underlying condition still needs professional follow-up.

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