Thanks for your input i've noted your experiences and will consider them when I experiment further, which won't be until I'm prepared.
Why did I feel tired? Well it could be one of or a combination of the following.
It was getting late(10pm).
I have a disposition with MAOI class drugs.
Caffeine lag, I drink a lot of tea and coffee but had not that evening as I thought milk would be bad.
Coincidence.
Superstition.
Bad luck
The Tiredness come on before smoking the DMT which is why I smoked only a small amount.
The adjustments I'll make next time will be to experiment much earlier in the day when energy levels are naturally higher.