Drowsiness

Drowsiness refers to feeling abnormally sleepy during the day -- often with a strong tendency to actually fall asleep in inappropriate situations or at inappropriate times.

Sleepiness - during the day; Hypersomnia; Somnolence

Excessive daytime sleepiness (without a known cause) suggests the presence of a significant sleep disorder and is different from fatigue. Although depression, anxiety, stress, and boredom can contribute to excessive sleepiness, these conditions more typically cause fatigue and apathy.

• Self-imposed short sleep time
• Medications (tranquilizers, sleeping pills, antihistamines)
• Sleep disorders (such as sleep apnea syndrome and narcolepsy)
• Other medical conditions (such as hypothyroidism, hypercalcemia, and hypo/hypernatremia)