Sativas and Sativa dominant strains (such as Haze, Trainwreck, Sour Diesel) contain more THC to CBN and CBD. THC is the stuff that gives you more like a cerebral psychedelic high. It's affects are more "happy" and sometimes even hyperactive. These kind of strains are good for people who are lethargic and burnt out, people who want to explore open mindedness and insight, artists, and those who want to smoke only during the day time. It is not good for people who are very anxious, and paranoid as it may increase your anxiety severely.
Indicas and Indica dominant strains (such as Purple Kush, White Widow, Cali Orange) contain more CBD and CBN over THC. This means the high will be more of a couch-lock, relaxing, body high. This stuff can knock you out, so it's best used in the evening. It's great for people who need to relax, lessen and control pain, and just want to chill. It's not recommended to use during the day, as it will burn you out. These strains can be more "addictive" to some as it sometimes offers "opium" like effects.
Hi, no offense here, but just wanted to clarify some misinformation in this post. Sativas and Indicas both usually never have CBD in them. 99% of today's strains are THC potent and have little CBD to CBN in them.
To make matters more interesting, Indicas themselves are hardly ever even capable of being CBD-rich, but in fact tend to be genetically predisposed to be extremely potent in THC. The strongest usually have the capacity to achieve higher levels of THC than Sativas do.
It is a misconception that THC gives the energetic and sparkly Sativa effect, while CBD gives the more mellow, narcotic effect of the Indica strains. It is actually as of yet unknown why the two major strain-families differ so. It is believed that the terpenes that cause the flavor and aroma of specific strains may be responsible for the differing effects, Sativas having a more spicy/citrus/chemical terpene profile and Indicas generally possessing a more earthy/floral profile. There is much research being conducted on this very topic.
In actuality, the most CBD-rich strains on the market are all potent Sativas. Harlequin, ATF, Jamaican Lion, Soma A+, etc, are all pure Sativa or Sativa dominant strains. These are not very common, but it is very interesting that it is the Sativas that show the most potential for CBD.
In my experience CBD is not always calming either. It can help clear up the stupefying effects of a heavy duty strain like ATF (one I have a lot of experience with) and is supposedly anxiolytic, but my own experience has shown that even CBD-rich strains can be quite alerting and cause me a bit of nervousness. In fact, the ATF I have used has caused me to have even more of a trippy feel than a THC-rich strain like God's Gift, and this is something I do not always like.
CBN is a byproduct of the oxidation of THC and will usually contribute to the feeling of being "messed up" or "drunk" if present in high amounts.
Again sorry to barge in correcting here, but I feel its important to dispel this myth that Indicas are rich in CBD and therefore cause a narcotic effect.