Effect of exercise timing

I switched my exercise timing from morning to evening and also increased the duration to 40-45 minutes. Also, I have reduced my protein intake (no fish during lunch and dinner but an omlette at dinner). I did elliptical cross training (cycling movement for legs and rowing movement for hands and upper body) for 40-45 minutes (distance covered - 14 kilometers at a speed of average 19-20 km/hour) I have observed the following things.

1. Better sleep with dream recall
2. Ability to get up from sleep faster with the feeling of completed sleep
3. Increased energy especially in morning - get ready to office in 1 hour 30 minutes after getting up
4. Increased focus and sustained concentration
5. Decreased sense of daytime sleepiness especially post lunch dip or afternoon sleepiness
5. Increased motivation

Possible reasons:
1. Evening time may be the best time for exercise because of more muscle flexibility
2. Evening exercise may stabilize cortisol level.

Daytime Sleepiness - Post Lunch Drowsiness

For the last one week, I am not taking any supplements. During the lunch, I took cooked beans and cooked greens with dhall (Tamil: keerai koottu). My lunch consisted of little rice, one piece of fish (either cooked in a gravy or fried), cooked beans and cooked greens with dhall. After the lunch, I did not feel sleepy significantly. No sleepiness in the evening also. Today, I took lunch with little rice, fried unripe banana (Tamil: Vaazhaikkai poriyal) and one piece of fish (cooked in gravy). After 1 hour, I felt sleepy uncontrollably. In my office chair itself, I slept for 10-15 minutes. After waking up, I felt normal and slightly more energetic with increased concentration.

This suggests that, this kind of sleepiness is probably due to excessive serotonin release triggered by insulin release. May be like this: Lunch increases blood glucose rapidly --> rapid and increased insulin release --> amino acid uptake into muscles --> tryptophan uptake into brain --> more serotonin synthesis and release (low cortisol in the afternoon also favors enhanced serotonin release). But, I doubt that increased synthesis and subsequent release of serotonin may happen after increased uptake of tryptophan into brain within 1 hour. The serotonin synthesis might take more amount of time. I need to explore further on this.

Also, this may have something to do with glucose homeostasis. I need to explore this further. However, my hypothesis at present is the cooked beans and greens may have high insoluble dietary fiber which may reduce glycemic index and slow the rate of release of insulin which subsequently lead to slower increase in serotonergic neurotransmission.