Dad, 81, sleeps 7-8 hours but feels drowsy/sleepy all morning. no fatigue and is active. sign of serious sleep disorder? see a sleep spec. right away

Fatigue: There are a number of possible causes. Please have your dad start w/a visit to his primary care doctor who may do some blood work. If all is well physically perhaps he is under stimulated or depressed. This can be helped by a clinical psychologist. Peace and good health.

Maybe: This may be a sign of significant sleep apnea, which causes the body to avoid deep restorative sleep to maintain blood oxygen content. It is more common than many suspect & often responds to simple CPAP used with sleep, which permits the body to enter deeper sleep without oxygen periodic oxygen deficits. See your primary doc & maybe a sleep specialist for testing.