Hi.
Sleep problem or
insomnia may cause headache and
lethargy.
Irregular sleep wake cycle require proper treatment to maintain it regularly.Headache and lethargy wont occur after regular and sound sleep.
Sleep hygiene is essential to regulate sleep wake cycle.That includes
Certain routines and lifestyle modification will help you like
Fix sleep schedule and stick on it
No day time sleep
Exercise that makes you fatigue
Stress free activities and meditations
Avoid alcohol and smoking
Avoid heavy meal in dinner
Avoid tea cofffee soft drink at night
Use bed when you feel sleepy
Read upto when you will sleepy
No talking or use mobile in bed
Calm and cool bed room
All of this will help you to restore good sleep.
Go for psychological screening because psychological stress also can lead to sleep problem.so treatment of it will resolve it.
Medicines are also helpful but
consult psychiatrist before taking any medicines.
Glad to help you further.
Thank you.