The Two Things You Should Do In Bed
Getting the Most From Your Sleep Sanctuary
The bedroom is and should always be your sleep sanctuary. This is a guiding principle for a great night of sleep and the development of healthy sleep habits. And, ultimately, the goal should be to avoid any activities in your room (and in particular, your bed) other than sleeping.
When you save your bedroom only for sleep, the mind is able to get into “sleep mode" when you enter the room. This is similar to the sensation of energy you may feel when you walk into your gym, or the feeling of hunger you get walking into your favorite restaurant. Your brain creates an association between sleep and the bedroom, and it knows exactly what it should do in each of those situations to automatically prepare your body for the activity. The opposite is also true. Your body does not tend to get hungry while at the gym nor get energized for a workout when you walk into a restaurant.
Because of this, you can see why performing a lot of different activities in your bedroom can make sleep more challenging (i.e. watching tv in bed, doing work in your bedroom, eating in bed, etc.). For a lot of people, the bedroom has become the place where we watch TV, eat, do work, etc. and we have, in turn, developed bad sleeping habits. When you make a habit of doing many different activities in the bedroom, the brain doesn't know what to expect when you enter and thus no longer associates only sleep habits with your bed and bedroom.
Developing Proper Sleep Associations
When you make your bedroom less of a sleep sanctuary and more of a living space for all activities, this can make it harder to settle the brain down for sleep. And, this is also why a common treatment for insomnia is to leave the bed when not sleepy so that you don't spend excessive amounts of time awake while lying in bed. It's a technique called stimulus control. The goal is simple — you want your bed to be associated with only relaxation and sleep, not being awake.
Apart from simply disrupting your brain's match between sleep and the bed, doing other activities in bed can hurt sleep more directly. Watching TV in the bedroom/watching tv before bed or using your phone at night provides bright lights to your brain, which can't distinguish artificial light from sunlight. So, if your brain gets bright lights at night, it thinks it's still daytime and suppresses your natural sleep hormone melatonin. This leads to later bedtimes and less sleep.
Your Sleep Sanctuary Should Be Reserved For Two Activities Only...
So, besides sleeping, what is the second activity that's allowed in bed? Intimacy. But only because it's the most convenient (and probably safest) location for it. And in many cases, sex can also lead to relaxation. So, stick with only sleep and intimacy in the bedroom, and you may find yourself sleeping much better.