Drowsiness refers to feeling abnormally sleepy during the day. People who are drowsy may fall asleep in inappropriate situations or at inappropriate times.
Excessive daytime sleepiness (without a known cause) may be a sign of a sleep disorder. Depression, anxiety, stress, and boredom can all contribute to excessive sleepiness. But these conditions more often cause fatigue and apathy.
Drowsiness may be due to the following other reasons:
•Long-term (chronic) pain
•Having to work long hours or different shifts (nights, weekends)
•Long-term insomnia and other problems falling or staying asleep
•Changes in blood sodium levels (hyponatremia/hypernatremia)
•Medicines (tranquilizers, sleeping pills, antihistamines)
•Not sleeping long enough
•Sleep disorders (such as sleep apnea and narcolepsy)
•Too much calcium in your blood (hypercalcemia)
•Underactive thyroid (hypothyroidism)
You can relieve drowsiness by treating the cause of the problem. So it's always advisable to first determine the cause of your drowsiness and then follow the treatment accordingly.