Sleep Part 1: Mastering the Master Clock
In late 2006, I heard Frederick Goodwin MD, former director of the NIMH, speak to a DBSA group in Washington DC.
Managing sleep, he told the gathering, is vital to managing one’s bipolar. He went on to say that it was almost as if sleep were the main disorder and bipolar the downstream effect - or words to that effect.
I have observed a similar pattern. In all my years of attending support groups, I have yet to encounter an individual with a mood disorder who did not have serious problems dealing with sleep.
Earlier that year, Dr Goodwin signed for me a copy of the newly-minted second edition of his definitive book (with Kay Jamison PhD), “Manic-Depressive Illness: Bipolar Disorders and Recurrent Depression.” Chapter 16 is devoted exclusively to “Sleep and Circadian Rhythms.”
The authors make clear that although all of us have the equivalent of an internal 24-hour clock that regulates all manner of biological functions, this clock is programmed to respond to the external environment. The “master circadian clock” is located in the surprachismatic nuclei (SCN) of the anterior hypothalamus, just above the brain stem. The SCN cells react to light and dark input from the retina (via glutamate and other neurotransmitters) and from serotonin-producing neurons projecting from the midbrain.
Sleep and wakefulness are regulated by the interaction of circadian rhythms (process s and process c) paced by the SCN.
To function effectively, say the authors, the SCN must synchronize their 20,000 neurons, mainly via GABA neurotransmitters and the hormone melatonin. In humans, the master clock cycles at intervals slightly longer than 24 hours, relying on external cues (such as light and dark and temperature) to sync with the outside world.
Under normal conditions, circadian rhythms “homeostatically” maintain equilibrium. But these rhythms can be disturbed by long-distance travel, shift work, and other hazards of modern living. When the day is going right, our bodies experience a state of wakefulness characterized by: no melatonin secretion, higher core body temperature, decreasing sleepiness, decreasing EEG theta activity, decreasing REM sleep propensity, and decreasing cortisol levels.
At night, in a state of sleep, the reverse should be happening.
Sleep is vital to human functioning. Mammals deprived of sleep over two to three weeks die. Insufficient sleep results in the type of cognitive impairments that lead to all manner of accidents - motor vehicle, on-the-job, personal relationships.
On falling asleep, healthy adults enter non-REM (NREM) sleep, a period of rest and energy conservation. The brain literally cools, while heart rate and other physiological processes slow down. The eyes move slowly, and the muscles are relaxed. The brain progresses through four stages of NREM sleep (the latter stages characterized by slow delta wave activity). NREM sleep predominates during the first part of the night.
NREM sleep and thermoregulation are intertwined. Thus, a warm bath at night promotes NREM sleep.
REM (rapid eye movement) sleep, which is concentrated in the hours before waking, is far more noisy, marked by intense mental activity, vivid dreaming, and high brain metabolism. Paradoxically, while the brain is partying, large muscles are virtually paralyzed.
Goodwin and Jamison point out that too much or too little sleep is a feature of both depression and mania. They also mention that vital research is lacking, and therein we are faced with a series of chicken-and-egg conundrums. On the “chicken” side, a malfunction in the master clock may throw our other clocks out of phase, including those that regulate our moods. For instance:
We know that a disturbed night’s sleep is the royal road to mania. We also know that sleep deprivation is also the quickest way to bring a person out of depression, albeit temporarily.
There is a strong body of opinion that posits that those of us with bipolar are “phase-delayed” in our sleep cycle. In other words, it appears that a good many of us prefer to go to bed later and wake up later than the rest of the world.
Bipolars may be more sensitive to subtle disturbances in the master clock, borne out in research that shows our population is more susceptible to seasonal affective disorder than the general population (think of seasonal adjustments as a 'very long" circadian rhythm).
On the “egg” side, changes in routine tend to play havoc with the master clock. Thus, a depressed person who lies under the covers all day or someone in a state of mania who stays up all night is literally taking a hammer to the delicate watch works that makes our brains tick.
In “The Bipolar Workbook: Tools for Controlling Your Mood Swings,” Monica Basco PhD of the University of Texas Southwestern Medical Center gives the example of a person who gets a bright idea and stays up all night pursuing it, only to show up at work the next morning with a racing mind and in a state of exhaustion, primed for a major episode.
“The problem was not the project,” Dr Basco writes. “The problem was the timing.”
The bad news is that our overly-sensitive brains seem to set us up for failure. The good news is that by learning to manage just one thing - sleep - we are in a very good position to manage our entire illness. In other words, get the sleep right, and much of everything else falls into place.
Likewise, it is safe to say that is long as we play fast and loose with our sleep, recovery is highly problematic.
Lots more on sleep and what we can do about it in future articles …
John is an author and advocate for Mental Health. He wrote for HealthCentral as a patient expert for Depression and Bipolar Disorder.