There is no direct link between caffeine and depression, yet there are several side effects of caffeine that may indirectly cause depression or may aggravate existing feelings of depression. Caffeine causes sleeplessness, low blood sugar levels, and high anxiety — all triggers of depression. Although the connection between caffeine and depression isn't well researched, cutting caffeine out of the diet may improve one’s moods.
It is well known that caffeine can cause sleeplessness. Even one cup of coffee can cause jitteriness and insomnia in sensitive individuals. Sleeplessness can worsen any existing depression from which one may be suffering, turning a minor problem into a more serious one. To promote good sleeping habits, caffeinated beverages should be consumed in limited amounts and only during morning hours, if at all.
Studies also have shown a connection between caffeine and blood sugar levels. Too much caffeine encourages the body to produce insulin, a hormone that regulates blood sugar. Too much insulin at the wrong time can cause low blood sugar levels, also known as hypoglycemia. Low blood sugar causes, among other symptoms, low energy levels, which may result in feelings of depression.
It is not only the side effect of hypoglycemia that causes caffeine to make one feel tired. Caffeine creates a quick release of the adrenaline hormone, which gives the body a brief feeling of energy, and dopamine, which causes the body to experience pleasure. Eventually when the caffeine wears off, the individual may experience a low, feeling short on energy and depressed.
Individuals whose depression is linked to anxiety typically should avoid caffeine. Caffeine has the unfortunate negative effect of stimulating the sympathetic nervous system, which controls the body’s anxiety and stress responses. Stimulation of the sympathetic nervous system can cause jitteriness and can make an individual less capable of handling stressful situations.
Caffeine and depression are also linked because of the symptoms associated with caffeine withdrawal. Caffeine withdrawal may cause headaches, irritability, fatigue and difficulty concentrating. Over an extended period, these symptoms can trigger feelings of depression or enhance existing feelings. If attempting to break the caffeine habit, individuals should go through the process gradually rather than quitting cold turkey; cutting down the caffeine intake daily until consumption ceases entirely may help reduce side effects.
It also is important to note that not everyone will be affected by the connection between caffeine and depression. The cause and effect relationship usually occurs only in individuals who are particularly sensitive to caffeine, and may not even happen in these individuals. Anyone who experiences severe feelings of depression should see the advice of a medical professional.