Thank you for asking such an interesting question.
Excessive daytime sleepiness is one of the most common sleep-related patient symptoms, and it affects an estimated 10 to 20 percent of the population. People with excessive daytime sleepiness are at risk of motor-vehicle and work-related incidents.
Causes of excessive daytime sleepiness
The first causative factor that came to my mind is that of poor sleep at night. Many people are anxious and worried at night and that affects the quality of sleep at night.
The second cause is not obstructive sleep apnea. This means that their sleep at night is interrupted as they gasp for air and have frequent arousals throughout the night. The sleep quality at night is hence compromised. As a person becomes more mature in age, he is likely to put on weight and the muscles involved in breathing are not as strong as before. All these are risk factors for obstructive sleep apnea.
Third, side effects of medications. Many medicines though taken at night may persist in the body and they may cause a person to feel sleepy in the daytime. Some sleeping pills and antidepressants (like mirtazapine) do have this side effect.
Other potential causes of excessive daytime sleepiness include certain medical and psychiatric conditions and sleep disorders, such as narcolepsy. The evaluation and management of excessive daytime sleepiness are based on the identification and treatment of underlying conditions (particularly obstructive sleep apnea), and the appropriate use of activating medications.
