The Link Between Sleep and Depression
There is evidence that there is a link between sleep and depression. Problems with sleeping, such as initial or terminal insomnia, multiple awakenings or hypersomnia are just three of the most common, if not classic, symptoms of depression. A decreased need for sleep can be seen as a sign of impending mania.
Depression is defined as a psychoneurotic or psychotic disorder which is distinguished in particular by symptoms such as sadness, inactivity, difficulty in thinking, difficulty in concentrating, a significant increase or decrease in appetite, significant increase in the need for sleep, feelings of inadequacy and suicidal thoughts. Sleep abnormalities are common symptoms of depression.
What is Normal Sleep?
Sleep is linked to numerous physiological changes like respiration, muscle tone, the secretion of hormones like the growth hormone, blood pressure and even cardiac function. It is a regular, repeated and easily two-sided state of a living organism which is demonstrated by relative inactivity and by a relative increase in the threshold of response to external stimuli relative to the waking state.
Sleep disturbances are closely monitored in clinical practice because changes in sleeping patterns ,(an increase in the need for, or lack of need for sleep) are seen as early symptoms of an imminent mental illness like depression. Clinical depression is associated with characteristic changes in the sleep physiology of the individual.
Stages of Sleep
When a person falls asleep, brain waves go through specific and characteristic changes.
Non-rapid Eye Movement (NREM) Sleep – in normal people, for those who are not depressed, sleep at this stage is a peaceful state where the pulse rate typically slows to only 5 to 10 beats per minute and is regular. Involuntary muscle movements are seen at this stage. Few, if any, rapid eye movements are displayed.
- Stage I – lightest stage of sleep
- Stage 2 – K complexes
- Stage 3 and 4 – Delta Waves or slow wave sleep (SWS)
Rapid Eye Movement (REM) Sleep – characterized by highly active brain and physiological activity levels quite similar to those seen when the individual is awake. In this state the oxygen levels in the brain increase significantly, while carbon dioxide (CO2) levels are depressed.
The Importance of Sleep
Most results of research conclude that sleep is a revitalizing and a homeostatic function which is crucial to the body’s normal thermoregulation and energy conservation. Long-drawn-out sleep deprivation can cause ego disorganization, hallucinations and delusions.
Sleep and Depression
Studies and research on sleep and depression have shown that the sleep electroencephalograms or EEGs of depressed individuals show substantial abnormalities. Some of the more common sleep abnormalities are a delay in the onset of sleep, a shortened rapid eye movement (REM) time between sleep and the first part of the REM period, an increase in the length of the first REM period and abnormal wave patterns during delta sleep. So significant were these results that research on mood disorders now includes the use of sleep EEGs for diagnostic purposes.
Growth Hormone and the Sleep and Depression Link
The growth hormone is also linked to sleep and depression symptomatology. Studies have shown a significant difference between depressed individuals and normal individuals in the regulation of the release of the growth hormone. People who are depressed show a “numbed” sleep-induced stimulation of the release of said hormones.
Unipolar and Bipolar Disorders and Sleep
The mood of the depressed individual may be either elevated or depressed. When the mood is elevated – mania – symptoms such as intensification of ideas, a decrease in the amount of sleep needed, heightened self-esteem and grandiose ideas can be exhibited.
When a depressed individual’s mood is low, on the other hand, the patient may experience a loss of energy and is uninterested in events unfolding around them. There are also increased feelings of guilt, difficulty in concentration, loss of appetite, suicidal thoughts and an increased need for sleep.