I have dealt with a fair amount of tiredness and fatigue, especially when taking anti-psychotic medication, which can act as a sedative (mostly during the night but still has an effect during the day).

Below are a list of suggestions I've found that may reduce tiredness:

Anti depressants.

Green tea (due to L-theanine & the small amount of caffeine).

Magnesium (especially if you are deficient in it).

Vitamin D (especially if you are deficient in it).

Fish oil tablets / omega-3 fish.

Staying hydrated.

Nibbling on nuts.

Eating healthy.

Smaller more frequent meals.

Exercising little and often throughout the day.

Taking power naps - short rests can help without disrupting nigh-time sleep.

Trying to go to bed at the same time and waking up each time at a similar time. Can help regulate your body's clock and reduces tiredness. It can be tempting to lie in on your days off but if you are struggling with tiredness it could be worth looking into this.

Mindfulness and meditation - Can help manage energy levels throughout the day. And anything that reduces stress can make you feel less tired.

Talking to people can make you more alert.

Cold face splashing / cold showers - the shock will wake you up a bit.

Cooler environments can increase your alertness

Music therapy & light therapy can increase alertness.

Gentle stretching.