I just received an email from Fiona who asks me for tips to overcome the fatigue and fogginess that settle in during Week 3 and Week 4 in a woman’s monthly cycle–which spans from the day after ovulation through the day before your next period–due to elevated levels of sedating progesterone and lower levels of estrogen. Fiona writes:

How can I get some pep during Week 3 with the super sleepy sedating progesterone slowing me down? It’s always such a severe shift for me from Week 1 & 2 which are vibrant and energised… then Week 3 & 4 … I’d be better off left in bed to sleep or read a book or watch a movie. I seem to lose all capability to focus & get stuff done.

Fiona points out that she doesn’t consume caffeine or sugar, so she’d like non-stimulant ways to overcome these sleepy hormonal effects.

I’m like Fiona–once my Week 3 rolls around, my mental and physical energy plummet sharply. Luckily, as a health journalist, I regularly report on research about ways to chase away fatigue and rev energy that don’t require caffeine or sugar. Here are five that I’ve written about in magazine articles and, based on using them myself with quite a bit of success, recommend for you:

1. Sneak in a nap

I know a daytime nap isn’t feasible for many women who have jobs, school, kids or other responsibilities that make an afternoon snooze impossible. But on the days you can, hit the sheets. Sleep researcher Sara C. Mednick, Ph.D., author of Take a Nap! Change your Life, has spent a career proving that naps can help replenish energy–even if you only have time for a short “micronap” of just a few minutes.

For those who, unlike Fiona, do drink caffeine, Mednick has also found that drinking a cup of caffeinated tea or coffee right before a nap helps revive you even more than napping alone. That’s because by the time you’ve woken up, the caffeine will have hit your system–so you’ll feel energized from your snooze as well as from the caffeine.

Bonus: Napping isn’t just for replenishing energy. A 2007 study in the Journal of Sleep Research shows that a daytime siesta also reverses a premenstrual bad mood, making you cheerier and less anxious. The reason? Nighttime sleep during your premenstrual week tends to be less restful due to plunging estrogen, which then causes irritability and tension. So, a daytime nap helps catch up on sleep lost while tossing and turning, rebalancing your emotions.

2. Bask in sunlight–or the light of a blue bulb

Numerous studies show that natural light is proven to rev alertness–and it can even revive you as much as a nap. That’s because sunlight contains a high amount of blue light, which is picked up by certain cells in your eyes’ retina (ganglion cells) and resets your body clock—so instead of feeling sleepy, you feel energized and alert.

But, what if you sit in a windowless room or live in a cloudy area? Try swapping a light bulb you sit near during daylight hours with one that has a slightly blue hue–like the GE Reveal or Chromalux Full Spectrum (available at Home Depot, Amazon and Walmart). This mimics natural sunlight, which helps rev mental energy, according to a study in the journal PLOS ONE. Just be sure not to use it in the evening or at night since this blue light may block the production of melatonin–a hormone that helps you sleep.

3. Save an interesting task for your least energetic hour

Tend to hit a slump in the mid-morning? After lunch? Before dinner? Pinpoint the time of day that’s the least energetic for you during the second half of your cycle, then during that time switch to an activity that’s fun, interesting or exciting. This could mean anything from taking a break to play an action video game or ride your skateboard to calling someone who makes your heart race (for instance, asking someone on a first date) or doing a creative part of a project. A 1994 study in the British Journal of Psychology shows that switching to an interesting activity helps you overcome a reduction in pep by engaging your brain.

4. Exercise for 10 minutes

A brisk 10-minute walk, bike ride, hula hooping or other aerobic workout is enough to lift your pep and mood, say Northern Arizona University researchers. That’s because it gets your blood pumping through your body and to your brain.

Boost the benefit by doing your exercise outdoors near nature. Research shows that working out by trees, plants, grass and other greenery is even more rejuvenating than when doing the same exercise indoors. One theory why is that the beauty of nature scenes is uplifting, so you get filled with positivity, which is invigorating.

5. Sniff rosemary

Stick a stem of rosemary in your purse, backpack or pocket, then whenever you need to feel more awake, take a whiff. Research (such as this and this) shows you’ll feel more mentally alert in minutes. Credit goes to certain compounds in the fragrant herb that stimulate your brain.