If you're not having sex in Starfield daily, you're missing out on a massive XP buff
The "Emotional Security" buff is one of Starfield's best, and true love is the only way to get it.
If you've been saving yourself for that one special Starfield romance partner in your playthrough, it turns out you've been missing out on a status effect that's arguably better than any single chem can provide. It's called "Emotional Security," and the only way to get it is by having sex. If only it were that easy, Starfield.
Emotional Security boosts XP gains by 15% for 24 real minutes. As shared by VG247, this is similar to the 10% XP "Well Rested" bonus you get for sleeping in a bed, but better because it's a higher number and also it means someone loves you.
No, seriously: there are no one-night stands in Starfield, so the only way to get busy in bed is to first romance one of the select few NPCs that are interested. Thankfully Starfield's companions set their standards very low, so it's easy to make them fall in love with you, but it does take some time. Just bring one along on your adventures and, as long as you're not constantly committing crimes they don't approve of (just like real life, wow), you'll periodically unlock special "flirt" options in conversations that eventually lead to love and marriage.
Once you're married, bringing your partner along as your companion will allow them to sleep in the same bed automatically. There are no sex cutscenes—Baldur's Gate 3 this is not—but your partner will make a saucy comment as you're waking up, some of which were shared by the ESRB months before Starfield's release.
It's all very gushy and mechanical. If you're purely interested in the generous XP boost then there's no reason not to do this. There's no penality for letting time pass (unlike Baldur's Gate 3) and marriage doesn't lock you out of bringing other companions along, either.
However, I admit I'm hesitant simply because none of Starfield's four romanceable companions are my type. Sam Coe is cool, but dry. Sarah Morgan is a snoozefest. Barret is charming, but talks like a robot. And they're all too darn nice with the exception of Andreja, who has a little bit of an edge to balance out Constellation's unrelenting politeness.
The good news is the Well Rested buff also exists there for those who aren't ready for commitment, and it's much easier to get. Just sleep in any bed and you're rewarded with an extra 10% XP. Whichever sleep boost you get, I recommend hitting the hay right before you wrap up a few quests to get the most out of the bonus.