Hi, welcome to the forum, you may be probably having Circadian rhythm disorders. Due to long term sleep deprivation in night time or delay in sleep will lead to excessive day time sleep or sleepiness, tiredness, loss of concentration and even dizziness.
This usually has happened due to change in normal sleep-wake cycle. Disturbance of sleep cycle disorder can be due to stress, anxiety, depression. Even generalized disease or conditions can cause such symptoms; hence this needs to be ruled out.
Generalize conditions needed to be ruled out are anemia, Diabetes, steroid use, thyroid disorder (hypothyroidism), blood disorder and dietary deficiencies.
Firstly you need to undergo routine blood tests like complete blood count, differential count, ESR, Hb% and thyroid profile etc.
If stress is present, you need to go for relaxation exercises. Appropriate use of sedatives (benzodiazepines) will help you to get adequate sleep. I suggest you to consult a physician and get treated for recovery of normal sleep-awake cycle. Take care and regards.