If this is because he's gone...
1) REMEMBER this feeling for when your kids face change (like cosleeping to single, or crib to bed... And. Are. Up. Half. The. Night.
2) Try sleeping elsewhere. Even 'upside down' in your bed, or on HIS side... So that you're not waking up because you reach over and he's gone. But, if that doesn't work... Try the couch /futon / kids room, etc. just to train your brain to stop reaching out for him.
3) put on HIS deodorant & or Cologne before you go to sleep, so that whenever you move you smell 'him'.
If its because you're afraid to not wake when your kids need you...
1) LOUD monitor
2) sleep in their room (again just for a couple days)
If its habitual insomnia
1) Benadryl (active ingredient in Tylenol PM).
2) Doctor
If its being 'afraid' to be alone
1) Play music
2) Get a dog
3) invite/beg a friend /sister/parent over for a few nights
4) Leave lights on
Other random options
1) Sex before he leaves for work (even a quickie)
2) Hot chocolate or Vanilla Steamer (the only way warm milk tastes good to ME, but warm milk plain is just as effective)
3) Warm baths
4) Academic Pursuits (aka make your brain tired studying)
5) Cleaning (even typing that makes me sleepy!
6) Stay up SUPER late (4 hours of sleep in a block being better than 4 hours in 30 minute bites)
7) Move your toddlers bedtime EARLY (like 5pm) so you have an hour alone w hubs before work), and YOUR bedtime EARLY (like 730pm or 8pm) so you're both up super early and have time together as a family in the morning. This gives you and hour with H, 2 hours self time, 4am wake up. Lunch/Dinner w husband. Alternatively, instead of a half schedule, (as opposed to opposite schedules), you could MATCH his schedule. Doesn't mess kids up any more than traveling (aka, about a week to get over 'jet lag'.) I know a few families that do this (not many), but it only makes sense when kids aren't in school & the shift is longer than a few months.