Sleep, depression, fatigue, and insomnia

Sleep, Depression, Fatigue, and Insomnia

Henry Olders, MD, FRCPC
12 August 1998

Introduction
Recent research indicates that an important cause of depression may be sleeping too much; specifically, too much Rapid Eye Movement (REM) sleep. In those individuals without a genetic predisposition to depression, too much REM sleep can cause some depressive symptoms, such as chronic fatigue, lack of energy or motivation, or irritability.
How can a person possibly have too much sleep? Isn’t sleep good for you? And isn’t it stress that causes depression? Don’t a lot of depressed people have difficulty sleeping? For them, it sure doesn’t seem to be too much sleep!
Definitions
In explaining the first statement and responding to the questions, let’s first look at some terminology:
REM sleep: Rapid Eye Movement sleep, also called Paradoxical Sleep, is one component of normal sleep which typically takes up 20 to 25% of total sleep time. The first period of REM sleep usually occurs 90 minutes after falling asleep, and subsequent REM sleep episodes occur at 90 minute intervals. REM sleep seems to be the only component of sleep which is necessary for normal functioning of the brain, probably for long-term memory.
Fatigue: While many people use the terms “tired”, “fatigued”, “sleepy” interchangeably, for our purposes we should agree on certain meanings:
Acute fatigue: the physical or mental fatigue which you experience after working hard, for example, after running a marathon or writing a 6-hour exam. Acute fatigue gets better with rest or sleep.
Sleepiness: When you haven’t had enough sleep, you will experience spells of drowsiness or sleepiness at various times during the day. When sleepy, you will have difficulty concentrating, your eyelids will feel heavy, and you will fall asleep quickly if you lie down in a quiet place. Unless you’re trying to drive or need to stay awake, feeling sleepy can be quite pleasant if you have the opportunity to nap. If you’re overcome by drowsiness, a very brief nap of only 5 or 10 minutes will refresh you.
Even when you are getting enough sleep, it is quite normal to feel sleepy twice every 24 hours, in the early afternoon and again in the late evening.
Chronic fatigue: in contrast to acute fatigue, the chronic variety occurs without any physical or mental exertion. Chronic fatigue is common in depression, is the defining feature of chronic fatigue syndrome, and is the most distressing symptom experienced by cancer patients. Sufferers find that neither rest nor sleep relieves this type of fatigue. It manifests as a lack of energy, difficulty getting going, becoming exhausted quickly with most activities, feeling “dragged out”.
Normal Sleep
While the amount of sleep a person needs varies from one individual to another, on average young adults need about 7 or 8 hours. The need for sleep decreases with age, so that someone at age 65 will require on average about 6 hours for good functioning. Babies and children, of course, need considerably more sleep. While insufficient sleep causes drowsiness or sleepiness, is it possible to get too much sleep? What would happen if you slept excessively long?
It’s clear that we need some sleep, just like we need food, water, small amounts of vitamins and minerals, sunshine, oxygen, and so on. But too much of any of these necessities of life is bad for us. Too much food leads to obesity, diabetes, high blood pressure, heart disease, etc. Drinking too much water can cause seizures. Too much of certain vitamins is dangerous. Too much oxygen in premature infants causes blindness. Too much sun causes cataracts and skin cancer.
Similarly, too much sleep is bad for us also. Interestingly, the only component of sleep which seems to be necessary is also the one which causes problems if we get too much. This vital but potentially dangerous sleep component is REM sleep.
Studies suggest that too much REM sleep causes chronic fatigue, and in certain people may even lead to full-blown depression.
Excessive REM sleep
How can you get too much REM sleep? The simplest way is to sleep longer than you need. However, timing of sleep is important. It turns out that the amount of REM sleep a person gets increases throughout the night, from a minimum in the early evening to a maximum in the morning around 8 am, but the actual timing of the peak is probably tied to the time of sunrise. REM sleep follows a diurnal rhythm, and we know that the signal which most strongly programs our diurnal rhythms is light.
Thus, if you were to sleep 6 hours, from midnight to 6 am, about 25%, or 1.5 hours, of your sleep might be REM sleep. If your 6 hours of total sleep were taken earlier in the night, say from 9 pm to 3 am, the percent REM would be less, say 15%, for a total of 0.9 hours of REM sleep. But if you took the same 6 hours of sleep later in the morning, from 5 am to 11 am, the percent REM would be considerably higher, for example 40%, giving 2.4 hours of REM sleep. Thus, “sleeping in”, staying in bed past sunrise, may lead to excessive REM sleep. For example, many teenagers tend to sleep very late on weekends; when they finally get up, they have little energy or motivation, until late at night when they get into a party mood.
Studies show that people who sleep late tend to do less well in life: they are more likely to receive dishonorable discharges from the armed forces, and they change jobs more frequently. It may be that sleeping late, even when accompanied by insomnia, increases REM sleep to the point where it causes chronic fatigue or even depression, reducing the individual’s efficiency. As Benjamin Franklin said, “Early to bed and early to rise, makes a man healthy, wealthy, and wise!”
Certain medications can cause depression as a side effect; this includes reserpine, often prescribed for high blood pressure; propranolol, taken for angina; and benzodiazepines which are frequently used to treat anxiety or insomnia. Benzodiazepines include valium, ativan, serax, rivotril, dalmane. All these medications increase the amount of REM sleep under certain conditions, which may be how they cause depression or fatigue.
Treating Depression by Reducing REM Sleep
If too much REM sleep can cause depression, could we treat depressions by reducing REM sleep? A lot of evidence suggests that this works. For example, almost all antidepressant medications strongly suppress REM sleep. So do other antidepressant treatments, including electroconvulsive therapy, stimulants such as methylphenidate, and even exercise, which in some studies is as effective as medication against depression. But by far the simplest way to reduce REM sleep is simply to sleep less, or to sleep earlier in the night. It turns out that total sleep deprivation is a very effective treatment for depression, as is partial sleep deprivation when the person gets up earlier than usual. Unfortunately, even though staying awake all night leads to a total remission of depressive symptoms in about 70% of patients the very next afternoon, when the person has a sleep which includes REM sleep, the depression returns.
“But I don’t sleep too much; I have insomnia!”
“Fine”, you say, “it may certainly apply to other people that too much REM sleep causes their depression, but it can’t be true for me. I have difficulty falling asleep, when I do finally get to sleep, I keep waking up, and often I wake up early in the morning and I can’t get back to sleep without medication! I barely get any sleep at all!”
Why do people have insomnia (difficulty sleeping)? Some people drink too much caffeine, whether in coffee, tea, or in soft drinks; this keeps them awake. Others may be very very anxious about something. Severe pain may keep still others awake. But it’s very likely that most cases of chronic insomnia are caused by people who attempt to sleep more than they need.
When a man retires and has a lot of time on his hands, he may be tempted to increase his time in bed or simply take a nap every day. A woman who has just lost a spouse may attempt to escape from her grief and sadness through sleep. Physical illness often causes people to sleep more. More sleep means more REM sleep, which if excessive may cause chronic fatigue in the short term and frank depression if it continues.
But more sleep may also mean exceeding the individual’s sleep need. When this occurs, the person will encounter difficulty falling asleep or staying asleep; this is called insomnia.
Most people with insomnia believe they’re not getting enough sleep, however, and most researchers in the field would agree. But if these people were truly sleep deprived, they would be sleepy or drowsy during the day. In fact, insomniacs are more alert during the day than other people, and they are less sleepy than normals. Careful questioning of an insomniac’s sleep habits frequently reveals that the person spends more time in bed than people without insomnia. For example, a person who has tossed and turned all night may be convinced that he should sleep late to make up, or even take the morning off work or school. These attitudes about sleep, even though incorrect, are very resistant to change.
To compound the problem, people with insomnia frequently take sleeping pills, most often benzodiazepines. These medications do increase the amount of sleep; thus they also increase the amount of REM sleep, and in this way worsen depression. The following flow chart illustrates these vicious cycles:

Evaluation and Treatment
The following approach to evaluation and treatment has been useful in clinic settings:
Assess for symptoms of fatigue, insomnia, depression, and anxiety; Time course, severity, precipitating factors, and previous history of these and other disorders is important;
Rule out medical disorders which can be responsible for symptoms, such as thyroid disease, anemia, sleep apnea, and so on;
The following table describes treatment strategies:

fatigue
insomnia
depression
anxiety
staying in bed past 7 am
get up at 6 am

get up at 6 am
get up at 6 am
time in bed exceeds 6-7 hours

reduce time in bed to 6 hours or less

regular use of sleep or antianxiety medications
taper and discontinue medication
switch to a an antidepressant such as trazodone
taper and discontinue medication

little or no exercise
30 min. exercise 3 times weekly
30 min. exercise 3 times weekly
30 min. exercise 3 times weekly
30 min. exercise 3 times weekly
daytime naps
shorten naps to 15 min
shorten naps to 15 min
shorten naps to 15 min
shorten naps to 15 min
a trial of early rising has not worked

trial of antidepressant medication

Are there any negatives to reducing sleep time, or getting up early? Yes! If you reduce your sleep time to less than you need, you will experience daytime drowsiness at times other than the normal early afternoon. If you become sleepy while driving or operating potentially dangerous equipment, a serious accident could result, with possibly fatal results. Never drive or operate machinery when sleepy! Instead, take a brief nap (15-20 minutes maximum) which is refreshing; longer naps cause sluggishness and torpor.
In addition to getting up early, taking short naps when sleepy, and reducing time in bed if you experience insomnia, it may also be helpful to open the drapes or blinds in your bedroom at least partially so that the early morning light will enter your bedroom even while you’re asleep. Light seems to be the signal which controls the timing of your body’s diurnal rhythms, including the REM sleep rhythm.

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