There's a genetic component to caffeine metabolism.
"P-450 1A2, which is coded for by the gene CYP1A2, is the primary isoenzyme responsible for the demethylation of caffeine into dimethylxanthine metabolites paraxanthine, theobromine, and theophylline (Lelo et al. 1986; Miners and Birkett 1996). Each of these metabolites is subjected to further demethylation into monomethylxanthines (Miners and Birkett 1996). Variation in the CYP1A2 activity, both within and between individuals, represents a major source of variability in pharmaco-kinetics of caffeine. The clearance of caffeine can vary to up to 40-fold within and between individuals (Kalow and Tang 1991; Kashuba et al. 1998)."
After 2 and a half months of no caffeine whatsoever (cut out chocolate, coke, coffee) I decided to try drinking coffee again. Caloric requirements to go up, pulse goes up, helps during the colder days, easier to stay warm. The physical benefits are good. However, my sleep definitely suffers. The timing or the amount of caffeine doesn't matter. I never wake up feeling rested. 3 days after quitting all caffeine, I start sleeping soundly. Wake up refreshed. Missing out on sleep is not an option. Bad sleep seems to give me depression and a host of other health problems (you don't say).
I'm way better off caffeine and you might be too if you're a slow metabolizer and thus by the time you go to sleep, you're still under the effect of caffeine, even though you it's been hours since you last felt the mental effects.
Genetics of caffeine consumption and responses to caffeine
Caffeine is widely consumed in foods and beverages and is also used for a variety of medical purposes. Despite its widespread use, relatively little is understood regarding how genetics affects consumption, acute response, or the long-term effects of ...
www.ncbi.nlm.nih.gov
"P-450 1A2, which is coded for by the gene CYP1A2, is the primary isoenzyme responsible for the demethylation of caffeine into dimethylxanthine metabolites paraxanthine, theobromine, and theophylline (Lelo et al. 1986; Miners and Birkett 1996). Each of these metabolites is subjected to further demethylation into monomethylxanthines (Miners and Birkett 1996). Variation in the CYP1A2 activity, both within and between individuals, represents a major source of variability in pharmaco-kinetics of caffeine. The clearance of caffeine can vary to up to 40-fold within and between individuals (Kalow and Tang 1991; Kashuba et al. 1998)."
After 2 and a half months of no caffeine whatsoever (cut out chocolate, coke, coffee) I decided to try drinking coffee again. Caloric requirements to go up, pulse goes up, helps during the colder days, easier to stay warm. The physical benefits are good. However, my sleep definitely suffers. The timing or the amount of caffeine doesn't matter. I never wake up feeling rested. 3 days after quitting all caffeine, I start sleeping soundly. Wake up refreshed. Missing out on sleep is not an option. Bad sleep seems to give me depression and a host of other health problems (you don't say).
I'm way better off caffeine and you might be too if you're a slow metabolizer and thus by the time you go to sleep, you're still under the effect of caffeine, even though you it's been hours since you last felt the mental effects.