Sleepy When Hungry

The title says it all. Is it normal? I felt so sleepy that I could not focus on my work until I eat some food to regain my focus.

You may not be taking in enough nutrition in your normal diet and so just need to eat more. Make sure you are taking in adequate calories in regular meals. It should be 2,000 calories for women and 2,500 for men,but that is only a general guide.
If you are satisfied that your diet is adequate then see your doctor…you may need testing for diabetes, even if you have no other signs.

Maybe possible your sugar levels are low too? May lack on vitamin D??? -just playing devils advocaate here

if I attach the photo of my meal, can you estimate how much calories it have?

I always wonder that my symptom related to hypoglycemia. Since you mention about vitamin D lacks, I did some research, and now I wonder if I had enough vitamin D.

Since quarantine, my meals has changed. Anyway I’m gonna share my usual meal(before quarantine) throughout the day. Hope you can evaluate my meal and make hypothesis out of it.

Morning
7am: 2 Eggs(in the form of Soup), 30g Instant Chocolate drink+Honey(1/2 tbsp)
10am: Some chicken idk probably around 50g bought from food stall

Lunch
2pm: One plate of rice, half of chicken breast, 30g Instant Chocolate drink+Instant Coffee(1/2 tbsp)

Dinner
7pm: One plate of rice, another half of chicken breast

That is quite low in a calories count. About 1400 at a rough guess. Its not very balanced either. You need more fruit and vegetables and more protein. Milk, cheese, and yogurt. No more instant chocolate or honey.
What is your weight and height?

i wouldnt know as im not a doctor - I was just putting a suggestion forward . i have to say I hate chocolate in any form & I dont mind eggs but not in the form of a soup -I cant have honey because its too high in sugar for me

Apart from that -I love chicken & rice

5ft 4 in & about 78kg

158cm, 55kg

Fa, your weight seems OK for your height, so no problem there. Try having a snack of fruit or a yoghurt,or glass of milk around 4pm.
Are you getting enough sleep at night?

Most of the time I sleep for around 6 hours.

You should be sleeping around 8 hours. Just one more thing…I forgot to ask how old you are. If you are aged below e.g. 20yrs then your body is still growing and maturing and needs extra calories. I am assuming you are male,but if you are female then you may need extra iron in your diet. if you are over 20 yrs and doing a manual job or any heavy work you need extra calories or you will soon feel tired.